Refactor to unify scripts/categories as Executable

This commit consolidates scripts and categories under a unified
'Executable' concept. This simplifies the architecture and improves code
readability.

- Introduce subfolders within `src/domain` to segregate domain elements.
- Update class and interface names by removing the 'I' prefix in
  alignment with new coding standards.
- Replace 'Node' with 'Executable' to clarify usage; reserve 'Node'
  exclusively for the UI's tree component.

tests/unit/application/Parser/Executable/CategoryCollectionSpecificUtilities.spec.ts

@@ -0,0 +1,100 @@
+import { describe, it, expect } from 'vitest';
+import type { ISyntaxFactory } from '@/application/Parser/Executable/Script/Validation/Syntax/ISyntaxFactory';
+import { ScriptingLanguage } from '@/domain/ScriptingLanguage';
+import { LanguageSyntaxStub } from '@tests/unit/shared/Stubs/LanguageSyntaxStub';
+import { ScriptingDefinitionStub } from '@tests/unit/shared/Stubs/ScriptingDefinitionStub';
+import type { FunctionData } from '@/application/collections/';
+import { itEachAbsentCollectionValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { createFunctionDataWithCode } from '@tests/unit/shared/Stubs/FunctionDataStub';
+import { ScriptCompiler } from '@/application/Parser/Executable/Script/Compiler/ScriptCompiler';
+import { createCollectionUtilities } from '@/application/Parser/Executable/CategoryCollectionSpecificUtilities';
+import type { IScriptingDefinition } from '@/domain/IScriptingDefinition';
+import { createSyntaxFactoryStub } from '@tests/unit/shared/Stubs/SyntaxFactoryStub';
+
+describe('CategoryCollectionSpecificUtilities', () => {
+  describe('createCollectionUtilities', () => {
+    describe('functionsData', () => {
+      describe('can create with absent data', () => {
+        itEachAbsentCollectionValue<FunctionData>((absentValue) => {
+          // arrange
+          const context = new TextContext()
+            .withData(absentValue);
+          // act
+          const act = () => context.createCollectionUtilities();
+          // assert
+          expect(act).to.not.throw();
+        }, { excludeNull: true });
+      });
+    });
+  });
+  describe('compiler', () => {
+    it('constructed as expected', () => {
+      // arrange
+      const functionsData = [createFunctionDataWithCode()];
+      const syntax = new LanguageSyntaxStub();
+      const expected = new ScriptCompiler(functionsData, syntax);
+      const language = ScriptingLanguage.shellscript;
+      const factoryMock = createSyntaxFactoryStub(language, syntax);
+      const definition = new ScriptingDefinitionStub()
+        .withLanguage(language);
+      const context = new TextContext()
+        .withData(functionsData)
+        .withScripting(definition)
+        .withSyntaxFactory(factoryMock);
+      // act
+      const utilities = context.createCollectionUtilities();
+      // assert
+      const actual = utilities.compiler;
+      expect(actual).to.deep.equal(expected);
+    });
+  });
+  describe('syntax', () => {
+    it('set from syntax factory', () => {
+      // arrange
+      const language = ScriptingLanguage.shellscript;
+      const expected = new LanguageSyntaxStub();
+      const factoryMock = createSyntaxFactoryStub(language, expected);
+      const definition = new ScriptingDefinitionStub()
+        .withLanguage(language);
+      const context = new TextContext()
+        .withScripting(definition)
+        .withSyntaxFactory(factoryMock);
+      // act
+      const utilities = context.createCollectionUtilities();
+      // assert
+      const actual = utilities.syntax;
+      expect(actual).to.equal(expected);
+    });
+  });
+});
+
+class TextContext {
+  private functionsData: readonly FunctionData[] | undefined = [createFunctionDataWithCode()];
+
+  private scripting: IScriptingDefinition = new ScriptingDefinitionStub();
+
+  private syntaxFactory: ISyntaxFactory = createSyntaxFactoryStub();
+
+  public withScripting(scripting: IScriptingDefinition): this {
+    this.scripting = scripting;
+    return this;
+  }
+
+  public withData(data: readonly FunctionData[] | undefined): this {
+    this.functionsData = data;
+    return this;
+  }
+
+  public withSyntaxFactory(syntaxFactory: ISyntaxFactory): this {
+    this.syntaxFactory = syntaxFactory;
+    return this;
+  }
+
+  public createCollectionUtilities(): ReturnType<typeof createCollectionUtilities> {
+    return createCollectionUtilities(
+      this.functionsData,
+      this.scripting,
+      this.syntaxFactory,
+    );
+  }
+}

tests/unit/application/Parser/Executable/CategoryParser.spec.ts

@@ -0,0 +1,462 @@
+import { describe, it, expect } from 'vitest';
+import type { CategoryData, ExecutableData } from '@/application/collections/';
+import { type CategoryFactory, parseCategory } from '@/application/Parser/Executable/CategoryParser';
+import { type ScriptParser } from '@/application/Parser/Executable/Script/ScriptParser';
+import { type DocsParser } from '@/application/Parser/Executable/DocumentationParser';
+import { CategoryCollectionSpecificUtilitiesStub } from '@tests/unit/shared/Stubs/CategoryCollectionSpecificUtilitiesStub';
+import { CategoryDataStub } from '@tests/unit/shared/Stubs/CategoryDataStub';
+import { getAbsentCollectionTestCases } from '@tests/unit/shared/TestCases/AbsentTests';
+import { ExecutableType } from '@/application/Parser/Executable/Validation/ExecutableType';
+import { createScriptDataWithCall, createScriptDataWithCode } from '@tests/unit/shared/Stubs/ScriptDataStub';
+import type { ErrorWithContextWrapper } from '@/application/Parser/ContextualError';
+import { ErrorWrapperStub } from '@tests/unit/shared/Stubs/ErrorWrapperStub';
+import type { ExecutableValidatorFactory } from '@/application/Parser/Executable/Validation/ExecutableValidator';
+import { ExecutableValidatorStub, createExecutableValidatorFactoryStub } from '@tests/unit/shared/Stubs/ExecutableValidatorStub';
+import type { CategoryErrorContext, UnknownExecutableErrorContext } from '@/application/Parser/Executable/Validation/ExecutableErrorContext';
+import { CategoryStub } from '@tests/unit/shared/Stubs/CategoryStub';
+import { createCategoryFactorySpy } from '@tests/unit/shared/Stubs/CategoryFactoryStub';
+import { expectExists } from '@tests/shared/Assertions/ExpectExists';
+import { ScriptStub } from '@tests/unit/shared/Stubs/ScriptStub';
+import { ScriptParserStub } from '@tests/unit/shared/Stubs/ScriptParserStub';
+import { formatAssertionMessage } from '@tests/shared/FormatAssertionMessage';
+import { indentText } from '@tests/shared/Text';
+import { itThrowsContextualError } from '../ContextualErrorTester';
+import { itValidatesName, itValidatesDefinedData, itAsserts } from './Validation/ExecutableValidationTester';
+import { generateDataValidationTestScenarios } from './Validation/DataValidationTestScenarioGenerator';
+
+describe('CategoryParser', () => {
+  describe('parseCategory', () => {
+    describe('validation', () => {
+      describe('validates for name', () => {
+        // arrange
+        const expectedName = 'expected category name to be validated';
+        const category = new CategoryDataStub()
+          .withName(expectedName);
+        const expectedContext: CategoryErrorContext = {
+          type: ExecutableType.Category,
+          self: category,
+        };
+        itValidatesName((validatorFactory) => {
+          // act
+          new TestBuilder()
+            .withData(category)
+            .withValidatorFactory(validatorFactory)
+            .parseCategory();
+          // assert
+          return {
+            expectedNameToValidate: expectedName,
+            expectedErrorContext: expectedContext,
+          };
+        });
+      });
+      describe('validates for defined data', () => {
+        // arrange
+        const category = new CategoryDataStub();
+        const expectedContext: CategoryErrorContext = {
+          type: ExecutableType.Category,
+          self: category,
+        };
+        itValidatesDefinedData(
+          (validatorFactory) => {
+            // act
+            new TestBuilder()
+              .withData(category)
+              .withValidatorFactory(validatorFactory)
+              .parseCategory();
+            // assert
+            return {
+              expectedDataToValidate: category,
+              expectedErrorContext: expectedContext,
+            };
+          },
+        );
+      });
+      describe('validates that category has some children', () => {
+        const categoryName = 'test';
+        const testScenarios = generateDataValidationTestScenarios<CategoryData>({
+          expectFail: getAbsentCollectionTestCases<ExecutableData>().map(({
+            valueName, absentValue: absentCollectionValue,
+          }) => ({
+            description: `with \`${valueName}\` value as children`,
+            data: new CategoryDataStub()
+              .withName(categoryName)
+              .withChildren(absentCollectionValue as unknown as ExecutableData[]),
+          })),
+          expectPass: [{
+            description: 'has single children',
+            data: new CategoryDataStub()
+              .withName(categoryName)
+              .withChildren([createScriptDataWithCode()]),
+          }],
+        });
+        testScenarios.forEach(({
+          description, expectedPass, data: categoryData,
+        }) => {
+          describe(description, () => {
+            itAsserts({
+              expectedConditionResult: expectedPass,
+              test: (validatorFactory) => {
+                const expectedMessage = `"${categoryName}" has no children.`;
+                const expectedContext: CategoryErrorContext = {
+                  type: ExecutableType.Category,
+                  self: categoryData,
+                };
+                // act
+                try {
+                  new TestBuilder()
+                    .withData(categoryData)
+                    .withValidatorFactory(validatorFactory)
+                    .parseCategory();
+                } catch { /* It may throw due to assertions not being evaluated */ }
+                // assert
+                return {
+                  expectedErrorMessage: expectedMessage,
+                  expectedErrorContext: expectedContext,
+                };
+              },
+            });
+          });
+        });
+      });
+      describe('validates that a child is a category or a script', () => {
+        // arrange
+        const testScenarios = generateDataValidationTestScenarios<ExecutableData>({
+          expectFail: [{
+            description: 'child has incorrect properties',
+            data: { property: 'non-empty-value' } as unknown as ExecutableData,
+          }],
+          expectPass: [
+            {
+              description: 'child is a category',
+              data: new CategoryDataStub(),
+            },
+            {
+              description: 'child is a script with call',
+              data: createScriptDataWithCall(),
+            },
+            {
+              description: 'child is a script with code',
+              data: createScriptDataWithCode(),
+            },
+          ],
+        });
+        testScenarios.forEach(({
+          description, expectedPass, data: childData,
+        }) => {
+          describe(description, () => {
+            itAsserts({
+              expectedConditionResult: expectedPass,
+              test: (validatorFactory) => {
+                const expectedError = 'Executable is neither a category or a script.';
+                const parent = new CategoryDataStub()
+                  .withName('parent')
+                  .withChildren([new CategoryDataStub().withName('valid child'), childData]);
+                const expectedContext: UnknownExecutableErrorContext = {
+                  self: childData,
+                  parentCategory: parent,
+                };
+                // act
+                new TestBuilder()
+                  .withData(parent)
+                  .withValidatorFactory(validatorFactory)
+                  .parseCategory();
+                // assert
+                return {
+                  expectedErrorMessage: expectedError,
+                  expectedErrorContext: expectedContext,
+                };
+              },
+            });
+          });
+        });
+      });
+      describe('validates children recursively', () => {
+        describe('validates (1th-level) child data', () => {
+          // arrange
+          const expectedName = 'child category';
+          const child = new CategoryDataStub()
+            .withName(expectedName);
+          const parent = new CategoryDataStub()
+            .withName('parent')
+            .withChildren([child]);
+          const expectedContext: UnknownExecutableErrorContext = {
+            self: child,
+            parentCategory: parent,
+          };
+          itValidatesDefinedData(
+            (validatorFactory) => {
+              // act
+              new TestBuilder()
+                .withData(parent)
+                .withValidatorFactory(validatorFactory)
+                .parseCategory();
+              // assert
+              return {
+                expectedDataToValidate: child,
+                expectedErrorContext: expectedContext,
+              };
+            },
+          );
+        });
+        describe('validates that (2nd-level) child name', () => {
+          // arrange
+          const expectedName = 'grandchild category';
+          const grandChild = new CategoryDataStub()
+            .withName(expectedName);
+          const child = new CategoryDataStub()
+            .withChildren([grandChild])
+            .withName('child category');
+          const parent = new CategoryDataStub()
+            .withName('parent')
+            .withChildren([child]);
+          const expectedContext: CategoryErrorContext = {
+            type: ExecutableType.Category,
+            self: grandChild,
+            parentCategory: child,
+          };
+          itValidatesName((validatorFactory) => {
+            // act
+            new TestBuilder()
+              .withData(parent)
+              .withValidatorFactory(validatorFactory)
+              .parseCategory();
+            // assert
+            return {
+              expectedNameToValidate: expectedName,
+              expectedErrorContext: expectedContext,
+            };
+          });
+        });
+      });
+    });
+    describe('rethrows exception if category factory fails', () => {
+      // arrange
+      const givenData = new CategoryDataStub();
+      const expectedContextMessage = 'Failed to parse category.';
+      const expectedError = new Error();
+      // act & assert
+      itThrowsContextualError({
+        throwingAction: (wrapError) => {
+          const validatorStub = new ExecutableValidatorStub();
+          validatorStub.createContextualErrorMessage = (message) => message;
+          const factoryMock: CategoryFactory = () => {
+            throw expectedError;
+          };
+          new TestBuilder()
+            .withCategoryFactory(factoryMock)
+            .withValidatorFactory(() => validatorStub)
+            .withErrorWrapper(wrapError)
+            .withData(givenData)
+            .parseCategory();
+        },
+        expectedWrappedError: expectedError,
+        expectedContextMessage,
+      });
+    });
+    it('parses docs correctly', () => {
+      // arrange
+      const url = 'https://privacy.sexy';
+      const categoryData = new CategoryDataStub()
+        .withDocs(url);
+      const parseDocs: DocsParser = (data) => {
+        return [
+          `parsed docs: ${JSON.stringify(data)}`,
+        ];
+      };
+      const expectedDocs = parseDocs(categoryData);
+      const { categoryFactorySpy, getInitParameters } = createCategoryFactorySpy();
+      // act
+      const actualCategory = new TestBuilder()
+        .withData(categoryData)
+        .withCategoryFactory(categoryFactorySpy)
+        .withDocsParser(parseDocs)
+        .parseCategory();
+      // assert
+      const actualDocs = getInitParameters(actualCategory)?.docs;
+      expect(actualDocs).to.deep.equal(expectedDocs);
+    });
+    describe('parses expected subscript', () => {
+      it('parses single script correctly', () => {
+        // arrange
+        const expectedScript = new ScriptStub('expected script');
+        const scriptParser = new ScriptParserStub();
+        const childScriptData = createScriptDataWithCode();
+        const categoryData = new CategoryDataStub()
+          .withChildren([childScriptData]);
+        scriptParser.setupParsedResultForData(childScriptData, expectedScript);
+        const { categoryFactorySpy, getInitParameters } = createCategoryFactorySpy();
+        // act
+        const actualCategory = new TestBuilder()
+          .withData(categoryData)
+          .withScriptParser(scriptParser.get())
+          .withCategoryFactory(categoryFactorySpy)
+          .parseCategory();
+        // assert
+        const actualScripts = getInitParameters(actualCategory)?.scripts;
+        expectExists(actualScripts);
+        expect(actualScripts).to.have.lengthOf(1);
+        const actualScript = actualScripts[0];
+        expect(actualScript).to.equal(expectedScript);
+      });
+      it('parses multiple scripts correctly', () => {
+        // arrange
+        const expectedScripts = [
+          new ScriptStub('expected-first-script'),
+          new ScriptStub('expected-second-script'),
+        ];
+        const childrenData = [
+          createScriptDataWithCall(),
+          createScriptDataWithCode(),
+        ];
+        const scriptParser = new ScriptParserStub();
+        childrenData.forEach((_, index) => {
+          scriptParser.setupParsedResultForData(childrenData[index], expectedScripts[index]);
+        });
+        const categoryData = new CategoryDataStub()
+          .withChildren(childrenData);
+        const { categoryFactorySpy, getInitParameters } = createCategoryFactorySpy();
+        // act
+        const actualCategory = new TestBuilder()
+          .withScriptParser(scriptParser.get())
+          .withData(categoryData)
+          .withCategoryFactory(categoryFactorySpy)
+          .parseCategory();
+        // assert
+        const actualParsedScripts = getInitParameters(actualCategory)?.scripts;
+        expectExists(actualParsedScripts);
+        expect(actualParsedScripts.length).to.equal(expectedScripts.length);
+        expect(actualParsedScripts).to.have.members(expectedScripts);
+      });
+      it('parses all scripts with correct utilities', () => {
+        // arrange
+        const expected = new CategoryCollectionSpecificUtilitiesStub();
+        const scriptParser = new ScriptParserStub();
+        const childrenData = [
+          createScriptDataWithCode(),
+          createScriptDataWithCode(),
+          createScriptDataWithCode(),
+        ];
+        const categoryData = new CategoryDataStub()
+          .withChildren(childrenData);
+        const { categoryFactorySpy, getInitParameters } = createCategoryFactorySpy();
+        // act
+        const actualCategory = new TestBuilder()
+          .withData(categoryData)
+          .withCollectionUtilities(expected)
+          .withScriptParser(scriptParser.get())
+          .withCategoryFactory(categoryFactorySpy)
+          .parseCategory();
+        // assert
+        const actualParsedScripts = getInitParameters(actualCategory)?.scripts;
+        expectExists(actualParsedScripts);
+        const actualUtilities = actualParsedScripts.map(
+          (s) => scriptParser.getParseParameters(s)[1],
+        );
+        expect(
+          actualUtilities.every(
+            (actual) => actual === expected,
+          ),
+          formatAssertionMessage([
+            `Expected all elements to be ${JSON.stringify(expected)}`,
+            'All elements:',
+            indentText(JSON.stringify(actualUtilities)),
+          ]),
+        ).to.equal(true);
+      });
+    });
+    it('returns expected subcategories', () => {
+      // arrange
+      const expectedChildCategory = new CategoryStub(33);
+      const childCategoryData = new CategoryDataStub()
+        .withName('expected child category')
+        .withChildren([createScriptDataWithCode()]);
+      const categoryData = new CategoryDataStub()
+        .withName('category name')
+        .withChildren([childCategoryData]);
+      const { categoryFactorySpy, getInitParameters } = createCategoryFactorySpy();
+      // act
+      const actualCategory = new TestBuilder()
+        .withData(categoryData)
+        .withCategoryFactory((parameters) => {
+          if (parameters.name === childCategoryData.category) {
+            return expectedChildCategory;
+          }
+          return categoryFactorySpy(parameters);
+        })
+        .parseCategory();
+      // assert
+      const actualSubcategories = getInitParameters(actualCategory)?.subcategories;
+      expectExists(actualSubcategories);
+      expect(actualSubcategories).to.have.lengthOf(1);
+      expect(actualSubcategories[0]).to.equal(expectedChildCategory);
+    });
+  });
+});
+
+class TestBuilder {
+  private data: CategoryData = new CategoryDataStub();
+
+  private collectionUtilities:
+  CategoryCollectionSpecificUtilitiesStub = new CategoryCollectionSpecificUtilitiesStub();
+
+  private categoryFactory: CategoryFactory = () => new CategoryStub(33);
+
+  private errorWrapper: ErrorWithContextWrapper = new ErrorWrapperStub().get();
+
+  private validatorFactory: ExecutableValidatorFactory = createExecutableValidatorFactoryStub;
+
+  private docsParser: DocsParser = () => ['docs'];
+
+  private scriptParser: ScriptParser = new ScriptParserStub().get();
+
+  public withData(data: CategoryData) {
+    this.data = data;
+    return this;
+  }
+
+  public withCollectionUtilities(
+    collectionUtilities: CategoryCollectionSpecificUtilitiesStub,
+  ): this {
+    this.collectionUtilities = collectionUtilities;
+    return this;
+  }
+
+  public withCategoryFactory(categoryFactory: CategoryFactory): this {
+    this.categoryFactory = categoryFactory;
+    return this;
+  }
+
+  public withValidatorFactory(validatorFactory: ExecutableValidatorFactory): this {
+    this.validatorFactory = validatorFactory;
+    return this;
+  }
+
+  public withErrorWrapper(errorWrapper: ErrorWithContextWrapper): this {
+    this.errorWrapper = errorWrapper;
+    return this;
+  }
+
+  public withScriptParser(scriptParser: ScriptParser): this {
+    this.scriptParser = scriptParser;
+    return this;
+  }
+
+  public withDocsParser(docsParser: DocsParser): this {
+    this.docsParser = docsParser;
+    return this;
+  }
+
+  public parseCategory() {
+    return parseCategory(
+      this.data,
+      this.collectionUtilities,
+      {
+        createCategory: this.categoryFactory,
+        wrapError: this.errorWrapper,
+        createValidator: this.validatorFactory,
+        parseScript: this.scriptParser,
+        parseDocs: this.docsParser,
+      },
+    );
+  }
+}

tests/unit/application/Parser/Executable/DocumentationParser.spec.ts

@@ -0,0 +1,73 @@
+import { describe, it, expect } from 'vitest';
+import type { DocumentableData } from '@/application/collections/';
+import { parseDocs } from '@/application/Parser/Executable/DocumentationParser';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('DocumentationParser', () => {
+  describe('parseDocs', () => {
+    describe('throws when single documentation is missing', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const expectedError = 'missing documentation';
+        const data: DocumentableData = { docs: ['non empty doc 1', absentValue] };
+        // act
+        const act = () => parseDocs(data);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+    describe('throws when type is unexpected', () => {
+      // arrange
+      const expectedTypeError = 'docs field (documentation) must be an array of strings';
+      const wrongTypedValue = 22 as never;
+      const testCases: ReadonlyArray<{
+        readonly name: string;
+        readonly data: DocumentableData;
+      }> = [
+        {
+          name: 'given docs',
+          data: { docs: wrongTypedValue },
+        },
+        {
+          name: 'single doc',
+          data: { docs: ['non empty doc 1', wrongTypedValue] },
+        },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.name, () => {
+          // act
+          const act = () => parseDocs(testCase.data);
+          // assert
+          expect(act).to.throw(expectedTypeError);
+        });
+      }
+    });
+    it('returns empty when empty', () => {
+      // arrange
+      const empty: DocumentableData = { };
+      // act
+      const actual = parseDocs(empty);
+      // assert
+      expect(actual).to.have.lengthOf(0);
+    });
+    it('returns single item when string', () => {
+      // arrange
+      const url = 'https://privacy.sexy';
+      const expected = [url];
+      const sut: DocumentableData = { docs: url };
+      // act
+      const actual = parseDocs(sut);
+      // assert
+      expect(actual).to.deep.equal(expected);
+    });
+    it('returns all when array', () => {
+      // arrange
+      const expected = ['https://privacy.sexy', 'https://github.com/undergroundwires/privacy.sexy'];
+      const sut: DocumentableData = { docs: expected };
+      // act
+      const actual = parseDocs(sut);
+      // assert
+      expect(actual).to.deep.equal(expected);
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Expression/Expression.spec.ts

@@ -0,0 +1,240 @@
+import { describe, it, expect } from 'vitest';
+import { ExpressionPosition } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition';
+import { type ExpressionEvaluator, Expression } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/Expression';
+import type { IReadOnlyFunctionCallArgumentCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Argument/IFunctionCallArgumentCollection';
+import { FunctionCallArgumentCollectionStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub';
+import { FunctionParameterCollectionStub } from '@tests/unit/shared/Stubs/FunctionParameterCollectionStub';
+import { FunctionCallArgumentStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentStub';
+import { ExpressionEvaluationContextStub } from '@tests/unit/shared/Stubs/ExpressionEvaluationContextStub';
+import type { IPipelineCompiler } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/IPipelineCompiler';
+import { PipelineCompilerStub } from '@tests/unit/shared/Stubs/PipelineCompilerStub';
+import type { IReadOnlyFunctionParameterCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/IFunctionParameterCollection';
+import { itEachAbsentObjectValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import type { IExpressionEvaluationContext } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionEvaluationContext';
+import { expectExists } from '@tests/shared/Assertions/ExpectExists';
+import { formatAssertionMessage } from '@tests/shared/FormatAssertionMessage';
+
+describe('Expression', () => {
+  describe('ctor', () => {
+    describe('position', () => {
+      it('sets as expected', () => {
+        // arrange
+        const expected = new ExpressionPosition(0, 5);
+        // act
+        const actual = new ExpressionBuilder()
+          .withPosition(expected)
+          .build();
+        // assert
+        expect(actual.position).to.equal(expected);
+      });
+    });
+    describe('parameters', () => {
+      describe('defaults to empty array if absent', () => {
+        itEachAbsentObjectValue((absentValue) => {
+          // arrange
+          const parameters = absentValue;
+          // act
+          const actual = new ExpressionBuilder()
+            .withParameters(parameters)
+            .build();
+          // assert
+          expect(actual.parameters);
+          expect(actual.parameters.all);
+          expect(actual.parameters.all.length).to.equal(0);
+        }, { excludeNull: true });
+      });
+      it('sets as expected', () => {
+        // arrange
+        const expected = new FunctionParameterCollectionStub()
+          .withParameterName('firstParameterName')
+          .withParameterName('secondParameterName');
+        // act
+        const actual = new ExpressionBuilder()
+          .withParameters(expected)
+          .build();
+        // assert
+        expect(actual.parameters).to.deep.equal(expected);
+      });
+    });
+  });
+  describe('evaluate', () => {
+    describe('throws with invalid arguments', () => {
+      const testCases: readonly {
+        name: string,
+        context: IExpressionEvaluationContext,
+        expectedError: string,
+        sutBuilder?: (builder: ExpressionBuilder) => ExpressionBuilder,
+      }[] = [
+        {
+          name: 'throws when some of the required args are not provided',
+          sutBuilder: (i: ExpressionBuilder) => i.withParameterNames(['a', 'b', 'c'], false),
+          context: new ExpressionEvaluationContextStub()
+            .withArgs(new FunctionCallArgumentCollectionStub().withArgument('b', 'provided')),
+          expectedError: 'argument values are provided for required parameters: "a", "c"',
+        },
+        {
+          name: 'throws when none of the required args are not provided',
+          sutBuilder: (i: ExpressionBuilder) => i.withParameterNames(['a', 'b'], false),
+          context: new ExpressionEvaluationContextStub()
+            .withArgs(new FunctionCallArgumentCollectionStub().withArgument('c', 'unrelated')),
+          expectedError: 'argument values are provided for required parameters: "a", "b"',
+        },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.name, () => {
+          // arrange
+          const sutBuilder = new ExpressionBuilder();
+          if (testCase.sutBuilder) {
+            testCase.sutBuilder(sutBuilder);
+          }
+          const sut = sutBuilder.build();
+          // act
+          const act = () => sut.evaluate(testCase.context);
+          // assert
+          expect(act).to.throw(testCase.expectedError);
+        });
+      }
+    });
+    it('returns result from evaluator', () => {
+      // arrange
+      const evaluatorMock: ExpressionEvaluator = (c) => `"${c
+        .args
+        .getAllParameterNames()
+        .map((name) => context.args.getArgument(name))
+        .map((arg) => `${arg.parameterName}': '${arg.argumentValue}'`)
+        .join('", "')}"`;
+      const givenArguments = new FunctionCallArgumentCollectionStub()
+        .withArgument('parameter1', 'value1')
+        .withArgument('parameter2', 'value2');
+      const expectedParameterNames = givenArguments.getAllParameterNames();
+      const context = new ExpressionEvaluationContextStub()
+        .withArgs(givenArguments);
+      const expected = evaluatorMock(context);
+      const sut = new ExpressionBuilder()
+        .withEvaluator(evaluatorMock)
+        .withParameterNames(expectedParameterNames)
+        .build();
+      // arrange
+      const actual = sut.evaluate(context);
+      // assert
+      expect(expected).to.equal(actual, formatAssertionMessage([
+        `Given arguments: ${JSON.stringify(givenArguments)}`,
+        `Expected parameter names: ${JSON.stringify(expectedParameterNames)}`,
+      ]));
+    });
+    it('sends pipeline compiler as it is', () => {
+      // arrange
+      const expected = new PipelineCompilerStub();
+      const context = new ExpressionEvaluationContextStub()
+        .withPipelineCompiler(expected);
+      let actual: IPipelineCompiler | undefined;
+      const evaluatorMock: ExpressionEvaluator = (c) => {
+        actual = c.pipelineCompiler;
+        return '';
+      };
+      const sut = new ExpressionBuilder()
+        .withEvaluator(evaluatorMock)
+        .build();
+      // arrange
+      sut.evaluate(context);
+      // assert
+      expectExists(actual);
+      expect(expected).to.equal(actual);
+    });
+    describe('filters unused parameters', () => {
+      // arrange
+      const testCases = [
+        {
+          name: 'with a provided argument',
+          expressionParameters: new FunctionParameterCollectionStub()
+            .withParameterName('parameterToHave', false),
+          arguments: new FunctionCallArgumentCollectionStub()
+            .withArgument('parameterToHave', 'value-to-have')
+            .withArgument('parameterToIgnore', 'value-to-ignore'),
+          expectedArguments: [
+            new FunctionCallArgumentStub()
+              .withParameterName('parameterToHave').withArgumentValue('value-to-have'),
+          ],
+        },
+        {
+          name: 'without a provided argument',
+          expressionParameters: new FunctionParameterCollectionStub()
+            .withParameterName('parameterToHave', false)
+            .withParameterName('parameterToIgnore', true),
+          arguments: new FunctionCallArgumentCollectionStub()
+            .withArgument('parameterToHave', 'value-to-have'),
+          expectedArguments: [
+            new FunctionCallArgumentStub()
+              .withParameterName('parameterToHave').withArgumentValue('value-to-have'),
+          ],
+        },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.name, () => {
+          let actual: IReadOnlyFunctionCallArgumentCollection | undefined;
+          const evaluatorMock: ExpressionEvaluator = (c) => {
+            actual = c.args;
+            return '';
+          };
+          const context = new ExpressionEvaluationContextStub()
+            .withArgs(testCase.arguments);
+          const sut = new ExpressionBuilder()
+            .withEvaluator(evaluatorMock)
+            .withParameters(testCase.expressionParameters)
+            .build();
+          // act
+          sut.evaluate(context);
+          // assert
+          expectExists(actual);
+          const collection = actual;
+          const actualArguments = collection.getAllParameterNames()
+            .map((name) => collection.getArgument(name));
+          expect(actualArguments).to.deep.equal(testCase.expectedArguments);
+        });
+      }
+    });
+  });
+});
+
+class ExpressionBuilder {
+  private position: ExpressionPosition = new ExpressionPosition(0, 5);
+
+  private parameters?: IReadOnlyFunctionParameterCollection = new FunctionParameterCollectionStub();
+
+  public withPosition(position: ExpressionPosition) {
+    this.position = position;
+    return this;
+  }
+
+  public withEvaluator(evaluator: ExpressionEvaluator) {
+    this.evaluator = evaluator;
+    return this;
+  }
+
+  public withParameters(parameters: IReadOnlyFunctionParameterCollection | undefined) {
+    this.parameters = parameters;
+    return this;
+  }
+
+  public withParameterName(parameterName: string, isOptional = true) {
+    const collection = new FunctionParameterCollectionStub()
+      .withParameterName(parameterName, isOptional);
+    return this.withParameters(collection);
+  }
+
+  public withParameterNames(parameterNames: string[], isOptional = true) {
+    const collection = new FunctionParameterCollectionStub()
+      .withParameterNames(parameterNames, isOptional);
+    return this.withParameters(collection);
+  }
+
+  public build() {
+    return new Expression({
+      position: this.position,
+      evaluator: this.evaluator,
+      parameters: this.parameters,
+    });
+  }
+
+  private evaluator: ExpressionEvaluator = () => `[${ExpressionBuilder.name}] evaluated-expression`;
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionEvaluationContext.spec.ts

@@ -0,0 +1,57 @@
+import { describe, it, expect } from 'vitest';
+import { ExpressionEvaluationContext, type IExpressionEvaluationContext } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionEvaluationContext';
+import type { IReadOnlyFunctionCallArgumentCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Argument/IFunctionCallArgumentCollection';
+import type { IPipelineCompiler } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/IPipelineCompiler';
+import { FunctionCallArgumentCollectionStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub';
+import { PipelineCompilerStub } from '@tests/unit/shared/Stubs/PipelineCompilerStub';
+
+describe('ExpressionEvaluationContext', () => {
+  describe('ctor', () => {
+    describe('args', () => {
+      it('sets as expected', () => {
+        // arrange
+        const expected = new FunctionCallArgumentCollectionStub()
+          .withArgument('expectedParameter', 'expectedValue');
+        const builder = new ExpressionEvaluationContextBuilder()
+          .withArgs(expected);
+        // act
+        const sut = builder.build();
+        // assert
+        const actual = sut.args;
+        expect(actual).to.equal(expected);
+      });
+    });
+    describe('pipelineCompiler', () => {
+      it('sets as expected', () => {
+        // arrange
+        const expected = new PipelineCompilerStub();
+        const builder = new ExpressionEvaluationContextBuilder()
+          .withPipelineCompiler(expected);
+        // act
+        const sut = builder.build();
+        // assert
+        expect(sut.pipelineCompiler).to.equal(expected);
+      });
+    });
+  });
+});
+
+class ExpressionEvaluationContextBuilder {
+  private args: IReadOnlyFunctionCallArgumentCollection = new FunctionCallArgumentCollectionStub();
+
+  private pipelineCompiler: IPipelineCompiler = new PipelineCompilerStub();
+
+  public withArgs(args: IReadOnlyFunctionCallArgumentCollection) {
+    this.args = args;
+    return this;
+  }
+
+  public withPipelineCompiler(pipelineCompiler: IPipelineCompiler) {
+    this.pipelineCompiler = pipelineCompiler;
+    return this;
+  }
+
+  public build(): IExpressionEvaluationContext {
+    return new ExpressionEvaluationContext(this.args, this.pipelineCompiler);
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition.spec.ts

@@ -0,0 +1,213 @@
+import { describe, it, expect } from 'vitest';
+import { ExpressionPosition } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition';
+
+describe('ExpressionPosition', () => {
+  describe('ctor', () => {
+    it('sets as expected', () => {
+      // arrange
+      const expectedStart = 0;
+      const expectedEnd = 5;
+      // act
+      const sut = new ExpressionPosition(expectedStart, expectedEnd);
+      // assert
+      expect(sut.start).to.equal(expectedStart);
+      expect(sut.end).to.equal(expectedEnd);
+    });
+    describe('throws when invalid', () => {
+      // arrange
+      const testCases = [
+        { start: 5, end: 5, error: 'no length (start = end = 5)' },
+        { start: 5, end: 3, error: 'start (5) after end (3)' },
+        { start: -1, end: 3, error: 'negative start position: -1' },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.error, () => {
+          // act
+          const act = () => new ExpressionPosition(testCase.start, testCase.end);
+          // assert
+          expect(act).to.throw(testCase.error);
+        });
+      }
+    });
+  });
+  describe('isInInsideOf', () => {
+    // arrange
+    const testCases: readonly {
+      name: string,
+      sut: ExpressionPosition,
+      potentialParent: ExpressionPosition,
+      expectedResult: boolean,
+    }[] = [
+      {
+        name: 'true; when other contains sut inside boundaries',
+        sut: new ExpressionPosition(4, 8),
+        potentialParent: new ExpressionPosition(0, 10),
+        expectedResult: true,
+      },
+      {
+        name: 'true; when other contains sut with same upper boundary',
+        sut: new ExpressionPosition(4, 10),
+        potentialParent: new ExpressionPosition(0, 10),
+        expectedResult: true,
+      },
+      {
+        name: 'true; when other contains sut with same lower boundary',
+        sut: new ExpressionPosition(0, 8),
+        potentialParent: new ExpressionPosition(0, 10),
+        expectedResult: true,
+      },
+      {
+        name: 'false; when other is same as sut',
+        sut: new ExpressionPosition(0, 10),
+        potentialParent: new ExpressionPosition(0, 10),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when sut contains other',
+        sut: new ExpressionPosition(0, 10),
+        potentialParent: new ExpressionPosition(4, 8),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when sut starts and ends before other',
+        sut: new ExpressionPosition(0, 10),
+        potentialParent: new ExpressionPosition(15, 25),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when sut starts before other but ends inside other',
+        sut: new ExpressionPosition(0, 10),
+        potentialParent: new ExpressionPosition(5, 10),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when sut starts inside other but ends after other',
+        sut: new ExpressionPosition(5, 11),
+        potentialParent: new ExpressionPosition(0, 10),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when sut starts at same position but end after other',
+        sut: new ExpressionPosition(0, 11),
+        potentialParent: new ExpressionPosition(0, 10),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when sut ends at same positions but start before other',
+        sut: new ExpressionPosition(0, 10),
+        potentialParent: new ExpressionPosition(1, 10),
+        expectedResult: false,
+      },
+    ];
+    for (const testCase of testCases) {
+      it(testCase.name, () => {
+        // act
+        const actual = testCase.sut.isInInsideOf(testCase.potentialParent);
+        // assert
+        expect(actual).to.equal(testCase.expectedResult);
+      });
+    }
+  });
+  describe('isSame', () => {
+    // arrange
+    const testCases: readonly {
+      name: string,
+      sut: ExpressionPosition,
+      other: ExpressionPosition,
+      expectedResult: boolean,
+    }[] = [
+      {
+        name: 'true; when positions are same',
+        sut: new ExpressionPosition(0, 10),
+        other: new ExpressionPosition(0, 10),
+        expectedResult: true,
+      },
+      {
+        name: 'false; when start position is different',
+        sut: new ExpressionPosition(0, 10),
+        other: new ExpressionPosition(1, 10),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when end position is different',
+        sut: new ExpressionPosition(0, 10),
+        other: new ExpressionPosition(0, 11),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when both start and end positions are different',
+        sut: new ExpressionPosition(0, 10),
+        other: new ExpressionPosition(20, 30),
+        expectedResult: false,
+      },
+    ];
+    for (const testCase of testCases) {
+      it(testCase.name, () => {
+        // act
+        const actual = testCase.sut.isSame(testCase.other);
+        // assert
+        expect(actual).to.equal(testCase.expectedResult);
+      });
+    }
+  });
+  describe('isIntersecting', () => {
+    // arrange
+    const testCases: readonly {
+      name: string,
+      first: ExpressionPosition,
+      second: ExpressionPosition,
+      expectedResult: boolean,
+    }[] = [
+      {
+        name: 'true; when one contains other inside boundaries',
+        first: new ExpressionPosition(4, 8),
+        second: new ExpressionPosition(0, 10),
+        expectedResult: true,
+      },
+      {
+        name: 'true; when one starts inside other\'s ending boundary without being contained',
+        first: new ExpressionPosition(0, 10),
+        second: new ExpressionPosition(9, 15),
+        expectedResult: true,
+      },
+      {
+        name: 'true; when positions are the same',
+        first: new ExpressionPosition(0, 5),
+        second: new ExpressionPosition(0, 5),
+        expectedResult: true,
+      },
+      {
+        name: 'true; when one starts inside other\'s starting boundary without being contained',
+        first: new ExpressionPosition(5, 10),
+        second: new ExpressionPosition(5, 11),
+        expectedResult: true,
+      },
+      {
+        name: 'false; when one starts directly after other',
+        first: new ExpressionPosition(0, 10),
+        second: new ExpressionPosition(10, 20),
+        expectedResult: false,
+      },
+      {
+        name: 'false; when one starts after other with margin',
+        first: new ExpressionPosition(0, 10),
+        second: new ExpressionPosition(100, 200),
+        expectedResult: false,
+      },
+    ];
+    for (const testCase of testCases) {
+      it(testCase.name, () => {
+        // act
+        const actual = testCase.first.isIntersecting(testCase.second);
+        // assert
+        expect(actual).to.equal(testCase.expectedResult);
+      });
+      it(`reversed: ${testCase.name}`, () => {
+        // act
+        const actual = testCase.second.isIntersecting(testCase.first);
+        // assert
+        expect(actual).to.equal(testCase.expectedResult);
+      });
+    }
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPositionFactory.spec.ts

@@ -0,0 +1,99 @@
+import { describe, it, expect } from 'vitest';
+import { createPositionFromRegexFullMatch } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPositionFactory';
+import { ExpressionPosition } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition';
+import { itIsTransientFactory } from '@tests/unit/shared/TestCases/TransientFactoryTests';
+
+describe('ExpressionPositionFactory', () => {
+  describe('createPositionFromRegexFullMatch', () => {
+    describe('it is a transient factory', () => {
+      // arrange
+      const fakeMatch = createRegexMatch();
+      // act
+      const create = () => createPositionFromRegexFullMatch(fakeMatch);
+      // assert
+      itIsTransientFactory({
+        getter: create,
+        expectedType: ExpressionPosition,
+      });
+    });
+    it('creates a position with the correct start position', () => {
+      // arrange
+      const expectedStartPosition = 5;
+      const fakeMatch = createRegexMatch({
+        fullMatch: 'matched string',
+        matchIndex: expectedStartPosition,
+      });
+      // act
+      const position = createPositionFromRegexFullMatch(fakeMatch);
+      // assert
+      expect(position.start).toBe(expectedStartPosition);
+    });
+
+    it('creates a position with the correct end position', () => {
+      // arrange
+      const startPosition = 3;
+      const matchedString = 'matched string';
+      const expectedEndPosition = startPosition + matchedString.length;
+      const fakeMatch = createRegexMatch({
+        fullMatch: matchedString,
+        matchIndex: startPosition,
+      });
+      // act
+      const position = createPositionFromRegexFullMatch(fakeMatch);
+      // assert
+      expect(position.end).to.equal(expectedEndPosition);
+    });
+
+    it('creates correct position with capturing groups', () => {
+      // arrange
+      const startPosition = 20;
+      const fakeMatch = createRegexMatch({
+        fullMatch: 'matched string',
+        capturingGroups: ['group1', 'group2'],
+        matchIndex: startPosition,
+      });
+      // act
+      const position = createPositionFromRegexFullMatch(fakeMatch);
+      // assert
+      expect(position.start).toBe(startPosition);
+      expect(position.end).toBe(startPosition + fakeMatch[0].length);
+    });
+
+    describe('invalid values', () => {
+      it('throws an error if match.index is undefined', () => {
+        // arrange
+        const fakeMatch = createRegexMatch();
+        fakeMatch.index = undefined;
+        const expectedError = `Regex match did not yield any results: ${JSON.stringify(fakeMatch)}`;
+        // act
+        const act = () => createPositionFromRegexFullMatch(fakeMatch);
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+      it('throws an error for empty match', () => {
+        // arrange
+        const fakeMatch = createRegexMatch({
+          fullMatch: '',
+          matchIndex: 0,
+        });
+        const expectedError = `Regex match is empty: ${JSON.stringify(fakeMatch)}`;
+        // act
+        const act = () => createPositionFromRegexFullMatch(fakeMatch);
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+    });
+  });
+});
+
+function createRegexMatch(options?: {
+  readonly fullMatch?: string,
+  readonly capturingGroups?: readonly string[],
+  readonly matchIndex?: number,
+}): RegExpMatchArray {
+  const fullMatch = options?.fullMatch ?? 'default fake match';
+  const capturingGroups = options?.capturingGroups ?? [];
+  const fakeMatch: RegExpMatchArray = [fullMatch, ...capturingGroups];
+  fakeMatch.index = options?.matchIndex ?? 0;
+  return fakeMatch;
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/ExpressionsCompiler.spec.ts

@@ -0,0 +1,330 @@
+import { describe, it, expect } from 'vitest';
+import { ExpressionsCompiler } from '@/application/Parser/Executable/Script/Compiler/Expressions/ExpressionsCompiler';
+import type { IExpressionParser } from '@/application/Parser/Executable/Script/Compiler/Expressions/Parser/IExpressionParser';
+import { ExpressionStub } from '@tests/unit/shared/Stubs/ExpressionStub';
+import { ExpressionParserStub } from '@tests/unit/shared/Stubs/ExpressionParserStub';
+import { FunctionCallArgumentCollectionStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import type { IExpression } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/IExpression';
+
+describe('ExpressionsCompiler', () => {
+  describe('compileExpressions', () => {
+    describe('returns empty string when code is absent', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const expected = '';
+        const code = absentValue;
+        const sut = new SystemUnderTest();
+        const args = new FunctionCallArgumentCollectionStub();
+        // act
+        const value = sut.compileExpressions(code, args);
+        // assert
+        expect(value).to.equal(expected);
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+    describe('can compile nested expressions', () => {
+      it('when one expression is evaluated to a text that contains another expression', () => {
+        // arrange
+        const expectedResult = 'hello world!';
+        const rawCode = 'hello {{ firstExpression }}!';
+        const outerExpressionResult = '{{ secondExpression }}';
+        const expectedCodeAfterFirstCompilationRound = 'hello {{ secondExpression }}!';
+        const innerExpressionResult = 'world';
+        const expressionParserMock = new ExpressionParserStub()
+          .withResult(rawCode, [
+            new ExpressionStub()
+              // {{ firstExpression }
+              .withPosition(6, 27)
+              // Parser would hit the outer expression
+              .withEvaluatedResult(outerExpressionResult),
+          ])
+          .withResult(expectedCodeAfterFirstCompilationRound, [
+            new ExpressionStub()
+              // {{ secondExpression }}
+              .withPosition(6, 28)
+              // once the outer expression parser, compiler now parses its evaluated result
+              .withEvaluatedResult(innerExpressionResult),
+          ]);
+        const sut = new SystemUnderTest(expressionParserMock);
+        const args = new FunctionCallArgumentCollectionStub();
+        // act
+        const actual = sut.compileExpressions(rawCode, args);
+        // assert
+        expect(actual).to.equal(expectedResult);
+      });
+      describe('when one expression contains another hardcoded expression', () => {
+        it('when hardcoded expression is does not contain the hardcoded expression', () => {
+          // arrange
+          const expectedResult = 'hi !';
+          const rawCode = 'hi {{ outerExpressionStart }}delete {{ innerExpression }} me{{ outerExpressionEnd }}!';
+          const outerExpressionResult = '';
+          const innerExpressionResult = 'should not be there';
+          const expressionParserMock = new ExpressionParserStub()
+            .withResult(rawCode, [
+              new ExpressionStub()
+                // {{ outerExpressionStart }}delete {{ innerExpression }} me{{ outerExpressionEnd }}
+                .withPosition(3, 84)
+                .withEvaluatedResult(outerExpressionResult),
+              new ExpressionStub()
+                // {{ innerExpression }}
+                .withPosition(36, 57)
+                // Parser would hit both expressions as one is hardcoded in other
+                .withEvaluatedResult(innerExpressionResult),
+            ])
+            .withResult(expectedResult, []);
+          const sut = new SystemUnderTest(expressionParserMock);
+          const args = new FunctionCallArgumentCollectionStub();
+          // act
+          const actual = sut.compileExpressions(rawCode, args);
+          // assert
+          expect(actual).to.equal(expectedResult);
+        });
+        it('when hardcoded expression contains the hardcoded expression', () => {
+          // arrange
+          const expectedResult = 'hi game of thrones!';
+          const rawCode = 'hi {{ outerExpressionStart }} game {{ innerExpression }} {{ outerExpressionEnd }}!';
+          const expectedCodeAfterFirstCompilationRound = 'hi game {{ innerExpression }}!'; // outer is compiled first
+          const outerExpressionResult = 'game {{ innerExpression }}';
+          const innerExpressionResult = 'of thrones';
+          const expressionParserMock = new ExpressionParserStub()
+            .withResult(rawCode, [
+              new ExpressionStub()
+                // {{ outerExpressionStart }} game {{ innerExpression }} {{ outerExpressionEnd }}
+                .withPosition(3, 81)
+                // Parser would hit the outer expression
+                .withEvaluatedResult(outerExpressionResult),
+              new ExpressionStub()
+                // {{ innerExpression }}
+                .withPosition(35, 57)
+                // Parser would hit both expressions as one is hardcoded in other
+                .withEvaluatedResult(innerExpressionResult),
+            ])
+            .withResult(expectedCodeAfterFirstCompilationRound, [
+              new ExpressionStub()
+                // {{ innerExpression }}
+                .withPosition(8, 29)
+                // once the outer expression parser, compiler now parses its evaluated result
+                .withEvaluatedResult(innerExpressionResult),
+            ]);
+          const sut = new SystemUnderTest(expressionParserMock);
+          const args = new FunctionCallArgumentCollectionStub();
+          // act
+          const actual = sut.compileExpressions(rawCode, args);
+          // assert
+          expect(actual).to.equal(expectedResult);
+        });
+      });
+    });
+    describe('combines expressions as expected', () => {
+      // arrange
+      const code = 'part1 {{ a }} part2 {{ b }} part3';
+      const testCases = [
+        {
+          name: 'with ordered expressions',
+          expressions: [
+            new ExpressionStub().withPosition(6, 13).withEvaluatedResult('a'),
+            new ExpressionStub().withPosition(20, 27).withEvaluatedResult('b'),
+          ],
+          expected: 'part1 a part2 b part3',
+        },
+        {
+          name: 'unordered expressions',
+          expressions: [
+            new ExpressionStub().withPosition(20, 27).withEvaluatedResult('b'),
+            new ExpressionStub().withPosition(6, 13).withEvaluatedResult('a'),
+          ],
+          expected: 'part1 a part2 b part3',
+        },
+        {
+          name: 'with an optional expected argument that is not provided',
+          expressions: [
+            new ExpressionStub().withPosition(6, 13).withEvaluatedResult('a')
+              .withParameterNames(['optionalParameter'], true),
+            new ExpressionStub().withPosition(20, 27).withEvaluatedResult('b')
+              .withParameterNames(['optionalParameterTwo'], true),
+          ],
+          expected: 'part1 a part2 b part3',
+        },
+        {
+          name: 'with no expressions',
+          expressions: [],
+          expected: code,
+        },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.name, () => {
+          const expressionParserMock = new ExpressionParserStub()
+            .withResult(code, testCase.expressions);
+          const args = new FunctionCallArgumentCollectionStub();
+          const sut = new SystemUnderTest(expressionParserMock);
+          // act
+          const actual = sut.compileExpressions(code, args);
+          // assert
+          expect(actual).to.equal(testCase.expected);
+        });
+      }
+    });
+    describe('arguments', () => {
+      it('passes arguments to expressions as expected', () => {
+        // arrange
+        const expected = new FunctionCallArgumentCollectionStub()
+          .withArgument('test-arg', 'test-value');
+        const code = 'longer than 6 characters';
+        const expressions = [
+          new ExpressionStub().withPosition(0, 3),
+          new ExpressionStub().withPosition(3, 6),
+        ];
+        const expressionParserMock = new ExpressionParserStub()
+          .withResult(code, expressions);
+        const sut = new SystemUnderTest(expressionParserMock);
+        // act
+        sut.compileExpressions(code, expected);
+        // assert
+        const actualArgs = expressions
+          .flatMap((expression) => expression.callHistory)
+          .map((context) => context.args);
+        expect(
+          actualArgs.every((arg) => arg === expected),
+          `Expected: ${JSON.stringify(expected)}\n`
+          + `Actual: ${JSON.stringify(actualArgs)}\n`
+          + `Not equal: ${actualArgs.filter((arg) => arg !== expected)}`,
+        );
+      });
+    });
+    describe('throws when expressions are invalid', () => {
+      describe('throws when expected argument is not provided but used in code', () => {
+        // arrange
+        const testCases = [
+          {
+            name: 'empty parameters',
+            expressions: [
+              new ExpressionStub().withParameterNames(['parameter'], false),
+            ],
+            args: new FunctionCallArgumentCollectionStub(),
+            expectedError: 'parameter value(s) not provided for: "parameter" but used in code',
+          },
+          {
+            name: 'unnecessary parameter is provided',
+            expressions: [
+              new ExpressionStub().withParameterNames(['parameter'], false),
+            ],
+            args: new FunctionCallArgumentCollectionStub()
+              .withArgument('unnecessaryParameter', 'unnecessaryValue'),
+            expectedError: 'parameter value(s) not provided for: "parameter" but used in code',
+          },
+          {
+            name: 'multiple values are not provided',
+            expressions: [
+              new ExpressionStub().withParameterNames(['parameter1'], false),
+              new ExpressionStub().withParameterNames(['parameter2', 'parameter3'], false),
+            ],
+            args: new FunctionCallArgumentCollectionStub(),
+            expectedError: 'parameter value(s) not provided for: "parameter1", "parameter2", "parameter3" but used in code',
+          },
+          {
+            name: 'some values are provided',
+            expressions: [
+              new ExpressionStub().withParameterNames(['parameter1'], false),
+              new ExpressionStub().withParameterNames(['parameter2', 'parameter3'], false),
+            ],
+            args: new FunctionCallArgumentCollectionStub()
+              .withArgument('parameter2', 'value'),
+            expectedError: 'parameter value(s) not provided for: "parameter1", "parameter3" but used in code',
+          },
+          {
+            name: 'parameter names are not repeated in error message',
+            expressions: [
+              new ExpressionStub().withParameterNames(['parameter1', 'parameter1', 'parameter2', 'parameter2'], false),
+            ],
+            args: new FunctionCallArgumentCollectionStub(),
+            expectedError: 'parameter value(s) not provided for: "parameter1", "parameter2" but used in code',
+          },
+        ];
+        for (const testCase of testCases) {
+          it(testCase.name, () => {
+            const code = 'non-important-code';
+            const expressionParserMock = new ExpressionParserStub()
+              .withResult(code, testCase.expressions);
+            const sut = new SystemUnderTest(expressionParserMock);
+            // act
+            const act = () => sut.compileExpressions(code, testCase.args);
+            // assert
+            expect(act).to.throw(testCase.expectedError);
+          });
+        }
+      });
+      describe('throws when expression positions are unexpected', () => {
+        // arrange
+        const code = 'c'.repeat(30);
+        const testCases: readonly {
+          name: string,
+          expressions: readonly IExpression[],
+          expectedError: string,
+          expectedResult: boolean,
+        }[] = [
+          (() => {
+            const badExpression = new ExpressionStub().withPosition(0, code.length + 5);
+            const goodExpression = new ExpressionStub().withPosition(0, code.length - 1);
+            return {
+              name: 'an expression has out-of-range position',
+              expressions: [badExpression, goodExpression],
+              expectedError: `Expressions out of range:\n${JSON.stringify([badExpression])}`,
+              expectedResult: true,
+            };
+          })(),
+          (() => {
+            const duplicatedExpression = new ExpressionStub().withPosition(0, code.length - 1);
+            const uniqueExpression = new ExpressionStub().withPosition(0, code.length - 2);
+            return {
+              name: 'two expressions at the same position',
+              expressions: [duplicatedExpression, duplicatedExpression, uniqueExpression],
+              expectedError: `Instructions at same position:\n${JSON.stringify([duplicatedExpression, duplicatedExpression])}`,
+              expectedResult: true,
+            };
+          })(),
+          (() => {
+            const goodExpression = new ExpressionStub().withPosition(0, 5);
+            const intersectingExpression = new ExpressionStub().withPosition(5, 10);
+            const intersectingExpressionOther = new ExpressionStub().withPosition(7, 12);
+            return {
+              name: 'intersecting expressions',
+              expressions: [goodExpression, intersectingExpression, intersectingExpressionOther],
+              expectedError: `Instructions intersecting unexpectedly:\n${JSON.stringify([intersectingExpression, intersectingExpressionOther])}`,
+              expectedResult: true,
+            };
+          })(),
+        ];
+        for (const testCase of testCases) {
+          it(testCase.name, () => {
+            const expressionParserMock = new ExpressionParserStub()
+              .withResult(code, testCase.expressions);
+            const sut = new SystemUnderTest(expressionParserMock);
+            const args = new FunctionCallArgumentCollectionStub();
+            // act
+            const act = () => sut.compileExpressions(code, args);
+            // assert
+            expect(act).to.throw(testCase.expectedError);
+          });
+        }
+      });
+    });
+    it('calls parser with expected code', () => {
+      // arrange
+      const expected = 'expected-code';
+      const expressionParserMock = new ExpressionParserStub();
+      const sut = new SystemUnderTest(expressionParserMock);
+      const args = new FunctionCallArgumentCollectionStub();
+      // act
+      sut.compileExpressions(expected, args);
+      // assert
+      expect(expressionParserMock.callHistory).to.have.lengthOf(1);
+      expect(expressionParserMock.callHistory[0]).to.equal(expected);
+    });
+  });
+});
+
+class SystemUnderTest extends ExpressionsCompiler {
+  constructor(extractor: IExpressionParser = new ExpressionParserStub()) {
+    super(extractor);
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Parser/CompositeExpressionParser.spec.ts

@@ -0,0 +1,89 @@
+import { describe, it, expect } from 'vitest';
+import type { IExpression } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/IExpression';
+import type { IExpressionParser } from '@/application/Parser/Executable/Script/Compiler/Expressions/Parser/IExpressionParser';
+import { CompositeExpressionParser } from '@/application/Parser/Executable/Script/Compiler/Expressions/Parser/CompositeExpressionParser';
+import { ExpressionStub } from '@tests/unit/shared/Stubs/ExpressionStub';
+import { itEachAbsentCollectionValue } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('CompositeExpressionParser', () => {
+  describe('ctor', () => {
+    describe('throws when parsers are missing', () => {
+      itEachAbsentCollectionValue<IExpressionParser>((absentCollection) => {
+        // arrange
+        const expectedError = 'missing leafs';
+        const parsers = absentCollection;
+        // act
+        const act = () => new CompositeExpressionParser(parsers);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeUndefined: true, excludeNull: true });
+    });
+  });
+  describe('findExpressions', () => {
+    describe('returns result from parsers as expected', () => {
+      // arrange
+      const pool = [
+        new ExpressionStub(), new ExpressionStub(), new ExpressionStub(),
+        new ExpressionStub(), new ExpressionStub(),
+      ];
+      const testCases = [
+        {
+          name: 'from single parsing none',
+          parsers: [mockParser()],
+          expected: [],
+        },
+        {
+          name: 'from single parsing single',
+          parsers: [mockParser(pool[0])],
+          expected: [pool[0]],
+        },
+        {
+          name: 'from single parsing multiple',
+          parsers: [mockParser(pool[0], pool[1])],
+          expected: [pool[0], pool[1]],
+        },
+        {
+          name: 'from multiple parsers with each parsing single',
+          parsers: [
+            mockParser(pool[0]),
+            mockParser(pool[1]),
+            mockParser(pool[2]),
+          ],
+          expected: [pool[0], pool[1], pool[2]],
+        },
+        {
+          name: 'from multiple parsers with each parsing multiple',
+          parsers: [
+            mockParser(pool[0], pool[1]),
+            mockParser(pool[2], pool[3], pool[4])],
+          expected: [pool[0], pool[1], pool[2], pool[3], pool[4]],
+        },
+        {
+          name: 'from multiple parsers with only some parsing',
+          parsers: [
+            mockParser(pool[0], pool[1]),
+            mockParser(),
+            mockParser(pool[2]),
+            mockParser(),
+          ],
+          expected: [pool[0], pool[1], pool[2]],
+        },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.name, () => {
+          const sut = new CompositeExpressionParser(testCase.parsers);
+          // act
+          const result = sut.findExpressions('non-important-code');
+          // expect
+          expect(result).to.deep.equal(testCase.expected);
+        });
+      }
+    });
+  });
+});
+
+function mockParser(...result: IExpression[]): IExpressionParser {
+  return {
+    findExpressions: () => result,
+  };
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Parser/Regex/ExpressionRegexBuilder.spec.ts

@@ -0,0 +1,428 @@
+import { describe, it, expect } from 'vitest';
+import { ExpressionRegexBuilder } from '@/application/Parser/Executable/Script/Compiler/Expressions/Parser/Regex/ExpressionRegexBuilder';
+
+const AllWhitespaceCharacters = ' \t\n\r\v\f\u00A0';
+
+describe('ExpressionRegexBuilder', () => {
+  describe('expectCharacters', () => {
+    describe('expectCharacters', () => {
+      describe('escapes single character as expected', () => {
+        const charactersToEscape = ['.', '$'];
+        for (const character of charactersToEscape) {
+          it(`escapes ${character} as expected`, () => expectMatch(
+            character,
+            (act) => act.expectCharacters(character),
+            `${character}`,
+          ));
+        }
+      });
+      it('escapes multiple characters as expected', () => expectMatch(
+        '.I have no $$.',
+        (act) => act.expectCharacters('.I have no $$.'),
+        '.I have no $$.',
+      ));
+      it('adds characters as expected', () => expectMatch(
+        'return as it is',
+        (act) => act.expectCharacters('return as it is'),
+        'return as it is',
+      ));
+    });
+  });
+  describe('expectOneOrMoreWhitespaces', () => {
+    it('matches one whitespace', () => expectMatch(
+      ' ',
+      (act) => act.expectOneOrMoreWhitespaces(),
+      ' ',
+    ));
+    it('matches multiple whitespaces', () => expectMatch(
+      AllWhitespaceCharacters,
+      (act) => act.expectOneOrMoreWhitespaces(),
+      AllWhitespaceCharacters,
+    ));
+    it('matches whitespaces inside text', () => expectMatch(
+      `start${AllWhitespaceCharacters}end`,
+      (act) => act.expectOneOrMoreWhitespaces(),
+      AllWhitespaceCharacters,
+    ));
+    it('does not match non-whitespace characters', () => expectNonMatch(
+      'a',
+      (act) => act.expectOneOrMoreWhitespaces(),
+    ));
+  });
+  describe('captureOptionalPipeline', () => {
+    it('does not capture when no pipe is present', () => expectNonMatch(
+      'noPipeHere',
+      (act) => act.captureOptionalPipeline(),
+    ));
+    it('captures when input starts with pipe', () => expectCapture(
+      '| afterPipe',
+      (act) => act.captureOptionalPipeline(),
+      '| afterPipe',
+    ));
+    it('ignores without text before', () => expectCapture(
+      'stuff before | afterPipe',
+      (act) => act.captureOptionalPipeline(),
+      '| afterPipe',
+    ));
+    it('ignores without text before', () => expectCapture(
+      'stuff before | afterPipe',
+      (act) => act.captureOptionalPipeline(),
+      '| afterPipe',
+    ));
+    it('ignores whitespaces before the pipe', () => expectCapture(
+      '   | afterPipe',
+      (act) => act.captureOptionalPipeline(),
+      '| afterPipe',
+    ));
+    it('ignores text after whitespace', () => expectCapture(
+      '| first Pipe',
+      (act) => act.captureOptionalPipeline(),
+      '| first ',
+    ));
+    describe('non-greedy matching', () => { // so the rest of the pattern can work
+      it('non-letter character in pipe', () => expectCapture(
+        '| firstPipe | sec0ndpipe',
+        (act) => act.captureOptionalPipeline(),
+        '| firstPipe ',
+      ));
+    });
+  });
+  describe('captureUntilWhitespaceOrPipe', () => {
+    it('captures until first whitespace', () => expectCapture(
+      // arrange
+      'first ',
+      // act
+      (act) => act.captureUntilWhitespaceOrPipe(),
+      // assert
+      'first',
+    ));
+    it('captures until first pipe', () => expectCapture(
+      // arrange
+      'first|',
+      // act
+      (act) => act.captureUntilWhitespaceOrPipe(),
+      // assert
+      'first',
+    ));
+    it('captures all without whitespace or pipe', () => expectCapture(
+      // arrange
+      'all',
+      // act
+      (act) => act.captureUntilWhitespaceOrPipe(),
+      // assert
+      'all',
+    ));
+  });
+  describe('captureMultilineAnythingExceptSurroundingWhitespaces', () => {
+    describe('single line', () => {
+      it('captures a line without surrounding whitespaces', () => expectCapture(
+        // arrange
+        'line',
+        // act
+        (act) => act.captureMultilineAnythingExceptSurroundingWhitespaces(),
+        // assert
+        'line',
+      ));
+      it('captures a line with internal whitespaces intact', () => expectCapture(
+        `start${AllWhitespaceCharacters}end`,
+        (act) => act.captureMultilineAnythingExceptSurroundingWhitespaces(),
+        `start${AllWhitespaceCharacters}end`,
+      ));
+      it('excludes surrounding whitespaces', () => expectCapture(
+        // arrange
+        `${AllWhitespaceCharacters}single line\t`,
+        // act
+        (act) => act.captureMultilineAnythingExceptSurroundingWhitespaces(),
+        // assert
+        'single line',
+      ));
+    });
+    describe('multiple lines', () => {
+      it('captures text across multiple lines', () => expectCapture(
+        // arrange
+        'first line\nsecond line\r\nthird-line',
+        // act
+        (act) => act.captureMultilineAnythingExceptSurroundingWhitespaces(),
+        // assert
+        'first line\nsecond line\r\nthird-line',
+      ));
+      it('captures text with empty lines in between', () => expectCapture(
+        'start\n\nend',
+        (act) => act.captureMultilineAnythingExceptSurroundingWhitespaces(),
+        'start\n\nend',
+      ));
+      it('excludes surrounding whitespaces from multiline text', () => expectCapture(
+        // arrange
+        `  first line\nsecond line${AllWhitespaceCharacters}`,
+        // act
+        (act) => act.captureMultilineAnythingExceptSurroundingWhitespaces(),
+        // assert
+        'first line\nsecond line',
+      ));
+    });
+    describe('edge cases', () => {
+      it('does not capture for input with only whitespaces', () => expectNonCapture(
+        AllWhitespaceCharacters,
+        (act) => act.captureMultilineAnythingExceptSurroundingWhitespaces(),
+      ));
+    });
+  });
+  describe('expectExpressionStart', () => {
+    it('matches expression start without trailing whitespaces', () => expectMatch(
+      '{{expression',
+      (act) => act.expectExpressionStart(),
+      '{{',
+    ));
+    it('matches expression start with trailing whitespaces', () => expectMatch(
+      `{{${AllWhitespaceCharacters}expression`,
+      (act) => act.expectExpressionStart(),
+      `{{${AllWhitespaceCharacters}`,
+    ));
+    it('does not match whitespaces not directly after expression start', () => expectMatch(
+      '   {{expression',
+      (act) => act.expectExpressionStart(),
+      '{{',
+    ));
+    it('does not match if expression start is not present', () => expectNonMatch(
+      'noExpressionStartHere',
+      (act) => act.expectExpressionStart(),
+    ));
+  });
+  describe('expectExpressionEnd', () => {
+    it('matches expression end without preceding whitespaces', () => expectMatch(
+      'expression}}',
+      (act) => act.expectExpressionEnd(),
+      '}}',
+    ));
+    it('matches expression end with preceding whitespaces', () => expectMatch(
+      `expression${AllWhitespaceCharacters}}}`,
+      (act) => act.expectExpressionEnd(),
+      `${AllWhitespaceCharacters}}}`,
+    ));
+    it('does not capture whitespaces not directly before expression end', () => expectMatch(
+      'expression}}   ',
+      (act) => act.expectExpressionEnd(),
+      '}}',
+    ));
+    it('does not match if expression end is not present', () => expectNonMatch(
+      'noExpressionEndHere',
+      (act) => act.expectExpressionEnd(),
+    ));
+  });
+  describe('expectOptionalWhitespaces', () => {
+    describe('matching', () => {
+      it('matches multiple Unix lines', () => expectMatch(
+        // arrange
+        '\n\n',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        '\n\n',
+      ));
+      it('matches multiple Windows lines', () => expectMatch(
+        // arrange
+        '\r\n',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        '\r\n',
+      ));
+      it('matches multiple spaces', () => expectMatch(
+        // arrange
+        '  ',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        '  ',
+      ));
+      it('matches horizontal and vertical tabs', () => expectMatch(
+        // arrange
+        '\t\v',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        '\t\v',
+      ));
+      it('matches form feed character', () => expectMatch(
+        // arrange
+        '\f',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        '\f',
+      ));
+      it('matches a non-breaking space character', () => expectMatch(
+        // arrange
+        '\u00A0',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        '\u00A0',
+      ));
+      it('matches a combination of whitespace characters', () => expectMatch(
+        // arrange
+        AllWhitespaceCharacters,
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        AllWhitespaceCharacters,
+      ));
+      it('matches whitespace characters on different positions', () => expectMatch(
+        // arrange
+        '\ta\nb\rc\v',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+        // assert
+        '\t\n\r\v',
+      ));
+    });
+    describe('non-matching', () => {
+      it('a non-whitespace character', () => expectNonMatch(
+        // arrange
+        'a',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+      ));
+      it('multiple non-whitespace characters', () => expectNonMatch(
+        // arrange
+        'abc',
+        // act
+        (act) => act.expectOptionalWhitespaces(),
+      ));
+    });
+  });
+  describe('buildRegExp', () => {
+    it('sets global flag', () => {
+      // arrange
+      const expected = 'g';
+      const sut = new ExpressionRegexBuilder()
+        .expectOneOrMoreWhitespaces();
+      // act
+      const actual = sut.buildRegExp().flags;
+      // assert
+      expect(actual).to.equal(expected);
+    });
+    describe('can combine multiple parts', () => {
+      it('combines character and whitespace expectations', () => expectMatch(
+        'abc def',
+        (act) => act
+          .expectCharacters('abc')
+          .expectOneOrMoreWhitespaces()
+          .expectCharacters('def'),
+        'abc def',
+      ));
+      it('captures optional pipeline and text after it', () => expectCapture(
+        'abc | def',
+        (act) => act
+          .expectCharacters('abc ')
+          .captureOptionalPipeline(),
+        '| def',
+      ));
+      it('combines multiline capture with optional whitespaces', () => expectCapture(
+        '\n  abc  \n',
+        (act) => act
+          .expectOptionalWhitespaces()
+          .captureMultilineAnythingExceptSurroundingWhitespaces()
+          .expectOptionalWhitespaces(),
+        'abc',
+      ));
+      it('combines expression start, optional whitespaces, and character expectation', () => expectMatch(
+        '{{ abc',
+        (act) => act
+          .expectExpressionStart()
+          .expectOptionalWhitespaces()
+          .expectCharacters('abc'),
+        '{{ abc',
+      ));
+      it('combines character expectation, optional whitespaces, and expression end', () => expectMatch(
+        'abc }}',
+        (act) => act
+          .expectCharacters('abc')
+          .expectOptionalWhitespaces()
+          .expectExpressionEnd(),
+        'abc }}',
+      ));
+    });
+  });
+});
+
+enum MatchGroupIndex {
+  FullMatch = 0,
+  FirstCapturingGroup = 1,
+}
+
+function expectCapture(
+  input: string,
+  act: (regexBuilder: ExpressionRegexBuilder) => ExpressionRegexBuilder,
+  expectedCombinedCaptures: string | undefined,
+): void {
+  // arrange
+  const matchGroupIndex = MatchGroupIndex.FirstCapturingGroup;
+  // act
+  // assert
+  expectMatch(input, act, expectedCombinedCaptures, matchGroupIndex);
+}
+
+function expectNonMatch(
+  input: string,
+  act: (sut: ExpressionRegexBuilder) => ExpressionRegexBuilder,
+  matchGroupIndex = MatchGroupIndex.FullMatch,
+): void {
+  expectMatch(input, act, undefined, matchGroupIndex);
+}
+
+function expectNonCapture(
+  input: string,
+  act: (sut: ExpressionRegexBuilder) => ExpressionRegexBuilder,
+): void {
+  expectNonMatch(input, act, MatchGroupIndex.FirstCapturingGroup);
+}
+
+function expectMatch(
+  input: string,
+  act: (regexBuilder: ExpressionRegexBuilder) => ExpressionRegexBuilder,
+  expectedCombinedMatches: string | undefined,
+  matchGroupIndex = MatchGroupIndex.FullMatch,
+): void {
+  // arrange
+  const regexBuilder = new ExpressionRegexBuilder();
+  act(regexBuilder);
+  const regex = regexBuilder.buildRegExp();
+  // act
+  const allMatchGroups = Array.from(input.matchAll(regex));
+  // assert
+  const actualMatches = allMatchGroups
+    .filter((matches) => matches.length > matchGroupIndex)
+    .map((matches) => matches[matchGroupIndex])
+    .filter(Boolean) // matchAll returns `""` for full matches, `null` for capture groups
+    .flat();
+  const actualCombinedMatches = actualMatches.length ? actualMatches.join('') : undefined;
+  expect(actualCombinedMatches).equal(
+    expectedCombinedMatches,
+    [
+      '\n\n---',
+      'Expected combined matches:',
+      getTestDataText(expectedCombinedMatches),
+      'Actual combined matches:',
+      getTestDataText(actualCombinedMatches),
+      'Input:',
+      getTestDataText(input),
+      'Regex:',
+      getTestDataText(regex.toString()),
+      'All match groups:',
+      getTestDataText(JSON.stringify(allMatchGroups)),
+      `Match index in group: ${matchGroupIndex}`,
+      '---\n\n',
+    ].join('\n'),
+  );
+}
+
+function getTestDataText(data: string | undefined): string {
+  const outputPrefix = '\t> ';
+  if (data === undefined) {
+    return `${outputPrefix}undefined (no matches)`;
+  }
+  const getLiteralString = (text: string) => JSON.stringify(text).slice(1, -1);
+  const text = `${outputPrefix}\`${getLiteralString(data)}\``;
+  return text;
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Parser/Regex/RegexParser.spec.ts

@@ -0,0 +1,438 @@
+import { describe, it, expect } from 'vitest';
+import type {
+  ExpressionEvaluator, ExpressionInitParameters,
+} from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/Expression';
+import {
+  type PrimitiveExpression, RegexParser, type ExpressionFactory, type RegexParserUtilities,
+} from '@/application/Parser/Executable/Script/Compiler/Expressions/Parser/Regex/RegexParser';
+import { ExpressionPosition } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { collectExceptionMessage } from '@tests/unit/shared/ExceptionCollector';
+import { itThrowsContextualError } from '@tests/unit/application/Parser/ContextualErrorTester';
+import { ExpressionStub } from '@tests/unit/shared/Stubs/ExpressionStub';
+import { FunctionParameterCollectionStub } from '@tests/unit/shared/Stubs/FunctionParameterCollectionStub';
+import type { IExpression } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/IExpression';
+import { FunctionParameterStub } from '@tests/unit/shared/Stubs/FunctionParameterStub';
+import type { IReadOnlyFunctionParameterCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/IFunctionParameterCollection';
+import type { ExpressionPositionFactory } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPositionFactory';
+import { formatAssertionMessage } from '@tests/shared/FormatAssertionMessage';
+import { indentText } from '@tests/shared/Text';
+import type { FunctionParameterCollectionFactory } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameterCollectionFactory';
+
+describe('RegexParser', () => {
+  describe('findExpressions', () => {
+    describe('error handling', () => {
+      describe('throws when code is absent', () => {
+        itEachAbsentStringValue((absentValue) => {
+          // arrange
+          const expectedError = 'missing code';
+          const sut = new RegexParserConcrete({
+            regex: /unimportant/,
+          });
+          // act
+          const act = () => sut.findExpressions(absentValue);
+          // assert
+          const errorMessage = collectExceptionMessage(act);
+          expect(errorMessage).to.include(expectedError);
+        }, { excludeNull: true, excludeUndefined: true });
+      });
+      describe('rethrows regex match errors', () => {
+        // arrange
+        const expectedMatchError = new TypeError('String.prototype.matchAll called with a non-global RegExp argument');
+        const expectedMessage = 'Failed to match regex.';
+        const expectedCodeInMessage = 'unimportant code content';
+        const expectedRegexInMessage = /failing-regex-because-it-is-non-global/;
+        const expectedErrorMessage = buildRethrowErrorMessage({
+          message: expectedMessage,
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        });
+        itThrowsContextualError({
+          // act
+          throwingAction: (wrapError) => {
+            const sut = new RegexParserConcrete(
+              {
+                regex: expectedRegexInMessage,
+                utilities: {
+                  wrapError,
+                },
+              },
+            );
+            sut.findExpressions(expectedCodeInMessage);
+          },
+          // assert
+          expectedContextMessage: expectedErrorMessage,
+          expectedWrappedError: expectedMatchError,
+        });
+      });
+      describe('rethrows expression building errors', () => {
+        // arrange
+        const expectedMessage = 'Failed to build expression.';
+        const expectedInnerError = new Error('Expected error from building expression');
+        const {
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        } = createCodeAndRegexMatchingOnce();
+        const throwingExpressionBuilder = () => {
+          throw expectedInnerError;
+        };
+        const expectedErrorMessage = buildRethrowErrorMessage({
+          message: expectedMessage,
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        });
+        itThrowsContextualError({
+          // act
+          throwingAction: (wrapError) => {
+            const sut = new RegexParserConcrete(
+              {
+                regex: expectedRegexInMessage,
+                builder: throwingExpressionBuilder,
+                utilities: {
+                  wrapError,
+                },
+              },
+            );
+            sut.findExpressions(expectedCodeInMessage);
+          },
+          // assert
+          expectedWrappedError: expectedInnerError,
+          expectedContextMessage: expectedErrorMessage,
+        });
+      });
+      describe('rethrows position creation errors', () => {
+        // arrange
+        const expectedMessage = 'Failed to create position.';
+        const expectedInnerError = new Error('Expected error from position factory');
+        const {
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        } = createCodeAndRegexMatchingOnce();
+        const throwingPositionFactory = () => {
+          throw expectedInnerError;
+        };
+        const expectedErrorMessage = buildRethrowErrorMessage({
+          message: expectedMessage,
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        });
+        itThrowsContextualError({
+          // act
+          throwingAction: (wrapError) => {
+            const sut = new RegexParserConcrete(
+              {
+                regex: expectedRegexInMessage,
+                utilities: {
+                  createPosition: throwingPositionFactory,
+                  wrapError,
+                },
+              },
+            );
+            sut.findExpressions(expectedCodeInMessage);
+          },
+          // assert
+          expectedWrappedError: expectedInnerError,
+          expectedContextMessage: expectedErrorMessage,
+        });
+      });
+      describe('rethrows parameter creation errors', () => {
+        // arrange
+        const expectedMessage = 'Failed to create parameters.';
+        const expectedInnerError = new Error('Expected error from parameter collection factory');
+        const {
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        } = createCodeAndRegexMatchingOnce();
+        const throwingParameterCollectionFactory = () => {
+          throw expectedInnerError;
+        };
+        const expectedErrorMessage = buildRethrowErrorMessage({
+          message: expectedMessage,
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        });
+        itThrowsContextualError({
+          // act
+          throwingAction: (wrapError) => {
+            const sut = new RegexParserConcrete(
+              {
+                regex: expectedRegexInMessage,
+                utilities: {
+                  createParameterCollection: throwingParameterCollectionFactory,
+                  wrapError,
+                },
+              },
+            );
+            sut.findExpressions(expectedCodeInMessage);
+          },
+          // assert
+          expectedWrappedError: expectedInnerError,
+          expectedContextMessage: expectedErrorMessage,
+        });
+      });
+      describe('rethrows expression creation errors', () => {
+        // arrange
+        const expectedMessage = 'Failed to create expression.';
+        const expectedInnerError = new Error('Expected error from expression factory');
+        const {
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        } = createCodeAndRegexMatchingOnce();
+        const throwingExpressionFactory = () => {
+          throw expectedInnerError;
+        };
+        const expectedErrorMessage = buildRethrowErrorMessage({
+          message: expectedMessage,
+          code: expectedCodeInMessage,
+          regex: expectedRegexInMessage,
+        });
+        itThrowsContextualError({
+          // act
+          throwingAction: (wrapError) => {
+            const sut = new RegexParserConcrete(
+              {
+                regex: expectedRegexInMessage,
+                utilities: {
+                  createExpression: throwingExpressionFactory,
+                  wrapError,
+                },
+              },
+            );
+            sut.findExpressions(expectedCodeInMessage);
+          },
+          // assert
+          expectedWrappedError: expectedInnerError,
+          expectedContextMessage: expectedErrorMessage,
+        });
+      });
+    });
+    describe('handles matched regex correctly', () => {
+      // arrange
+      const testScenarios: readonly {
+        readonly description: string;
+        readonly regex: RegExp;
+        readonly code: string;
+      }[] = [
+        {
+          description: 'non-matching regex',
+          regex: /hello/g,
+          code: 'world',
+        },
+        {
+          description: 'single regex match',
+          regex: /hello/g,
+          code: 'hello world',
+        },
+        {
+          description: 'multiple regex matches',
+          regex: /l/g,
+          code: 'hello world',
+        },
+      ];
+      testScenarios.forEach(({
+        description, code, regex,
+      }) => {
+        describe(description, () => {
+          it('generates expressions for all matches', () => {
+            // arrange
+            const expectedTotalExpressions = Array.from(code.matchAll(regex)).length;
+            const sut = new RegexParserConcrete({
+              regex,
+            });
+            // act
+            const expressions = sut.findExpressions(code);
+            // assert
+            const actualTotalExpressions = expressions.length;
+            expect(actualTotalExpressions).to.equal(
+              expectedTotalExpressions,
+              formatAssertionMessage([
+                `Expected ${actualTotalExpressions} expressions due to ${expectedTotalExpressions} matches`,
+                `Expressions:\n${indentText(JSON.stringify(expressions, undefined, 2))}`,
+              ]),
+            );
+          });
+          it('builds primitive expressions for each match', () => {
+            const expected = Array.from(code.matchAll(regex));
+            const matches = new Array<RegExpMatchArray>();
+            const builder = (m: RegExpMatchArray): PrimitiveExpression => {
+              matches.push(m);
+              return createPrimitiveExpressionStub();
+            };
+            const sut = new RegexParserConcrete({
+              regex,
+              builder,
+            });
+            // act
+            sut.findExpressions(code);
+            // assert
+            expect(matches).to.deep.equal(expected);
+          });
+          it('sets positions correctly from matches', () => {
+            // arrange
+            const expectedMatches = [...code.matchAll(regex)];
+            const { createExpression, getInitParameters } = createExpressionFactorySpy();
+            const serializeRegexMatch = (match: RegExpMatchArray) => `[startPos:${match?.index ?? 'none'},length:${match?.[0]?.length ?? 'none'}]`;
+            const positionsForMatches = new Map<string, ExpressionPosition>(expectedMatches.map(
+              (expectedMatch) => [serializeRegexMatch(expectedMatch), new ExpressionPosition(1, 4)],
+            ));
+            const createPositionMock: ExpressionPositionFactory = (match) => {
+              const position = positionsForMatches.get(serializeRegexMatch(match));
+              return position ?? new ExpressionPosition(66, 666);
+            };
+            const sut = new RegexParserConcrete({
+              regex,
+              utilities: {
+                createExpression,
+                createPosition: createPositionMock,
+              },
+            });
+            // act
+            const expressions = sut.findExpressions(code);
+            // assert
+            const expectedPositions = [...positionsForMatches.values()];
+            const actualPositions = expressions.map((e) => getInitParameters(e)?.position);
+            expect(actualPositions).to.deep.equal(expectedPositions, formatAssertionMessage([
+              'Actual positions do not match the expected positions.',
+              `Expected total positions: ${expectedPositions.length} (due to ${expectedMatches.length} regex matches)`,
+              `Actual total positions: ${actualPositions.length}`,
+              `Expected positions:\n${indentText(JSON.stringify(expectedPositions, undefined, 2))}`,
+              `Actual positions:\n${indentText(JSON.stringify(actualPositions, undefined, 2))}`,
+            ]));
+          });
+        });
+      });
+    });
+    it('sets evaluator correctly from expression', () => {
+      // arrange
+      const { createExpression, getInitParameters } = createExpressionFactorySpy();
+      const expectedEvaluate = createEvaluatorStub();
+      const { code, regex } = createCodeAndRegexMatchingOnce();
+      const builder = (): PrimitiveExpression => ({
+        evaluator: expectedEvaluate,
+      });
+      const sut = new RegexParserConcrete({
+        regex,
+        builder,
+        utilities: {
+          createExpression,
+        },
+      });
+      // act
+      const expressions = sut.findExpressions(code);
+      // assert
+      expect(expressions).to.have.lengthOf(1);
+      const actualEvaluate = getInitParameters(expressions[0])?.evaluator;
+      expect(actualEvaluate).to.equal(expectedEvaluate);
+    });
+    it('sets parameters correctly from expression', () => {
+      // arrange
+      const expectedParameters: IReadOnlyFunctionParameterCollection['all'] = [
+        new FunctionParameterStub().withName('parameter1').withOptional(true),
+        new FunctionParameterStub().withName('parameter2').withOptional(false),
+      ];
+      const regex = /hello/g;
+      const code = 'hello';
+      const builder = (): PrimitiveExpression => ({
+        evaluator: createEvaluatorStub(),
+        parameters: expectedParameters,
+      });
+      const parameterCollection = new FunctionParameterCollectionStub();
+      const parameterCollectionFactoryStub
+      : FunctionParameterCollectionFactory = () => parameterCollection;
+      const { createExpression, getInitParameters } = createExpressionFactorySpy();
+      const sut = new RegexParserConcrete({
+        regex,
+        builder,
+        utilities: {
+          createExpression,
+          createParameterCollection: parameterCollectionFactoryStub,
+        },
+      });
+      // act
+      const expressions = sut.findExpressions(code);
+      // assert
+      expect(expressions).to.have.lengthOf(1);
+      const actualParameters = getInitParameters(expressions[0])?.parameters;
+      expect(actualParameters).to.equal(parameterCollection);
+      expect(actualParameters?.all).to.deep.equal(expectedParameters);
+    });
+  });
+});
+
+function buildRethrowErrorMessage(
+  expectedContext: {
+    readonly message: string;
+    readonly regex: RegExp;
+    readonly code: string;
+  },
+): string {
+  return [
+    expectedContext.message,
+    `Class name: ${RegexParserConcrete.name}`,
+    `Regex pattern used: ${expectedContext.regex}`,
+    `Code: ${expectedContext.code}`,
+  ].join('\n');
+}
+
+function createExpressionFactorySpy() {
+  const createdExpressions = new Map<IExpression, ExpressionInitParameters>();
+  const createExpression: ExpressionFactory = (parameters) => {
+    const expression = new ExpressionStub();
+    createdExpressions.set(expression, parameters);
+    return expression;
+  };
+  return {
+    createExpression,
+    getInitParameters: (expression) => createdExpressions.get(expression),
+  };
+}
+
+function createBuilderStub(): (match: RegExpMatchArray) => PrimitiveExpression {
+  return () => ({
+    evaluator: createEvaluatorStub(),
+  });
+}
+function createEvaluatorStub(): ExpressionEvaluator {
+  return () => `[${createEvaluatorStub.name}] evaluated code`;
+}
+
+function createPrimitiveExpressionStub(): PrimitiveExpression {
+  return {
+    evaluator: createEvaluatorStub(),
+  };
+}
+
+function createCodeAndRegexMatchingOnce() {
+  const code = 'expected code in context';
+  const regex = /code/g;
+  return { code, regex };
+}
+
+class RegexParserConcrete extends RegexParser {
+  private readonly builder: RegexParser['buildExpression'];
+
+  protected regex: RegExp;
+
+  public constructor(parameters?: {
+    regex?: RegExp,
+    builder?: RegexParser['buildExpression'],
+    utilities?: Partial<RegexParserUtilities>,
+  }) {
+    super({
+      wrapError: parameters?.utilities?.wrapError
+        ?? (() => new Error(`[${RegexParserConcrete}] wrapped error`)),
+      createPosition: parameters?.utilities?.createPosition
+        ?? (() => new ExpressionPosition(0, 5)),
+      createExpression: parameters?.utilities?.createExpression
+        ?? (() => new ExpressionStub()),
+      createParameterCollection: parameters?.utilities?.createParameterCollection
+        ?? (() => new FunctionParameterCollectionStub()),
+    });
+    this.builder = parameters?.builder ?? createBuilderStub();
+    this.regex = parameters?.regex ?? /unimportant/g;
+  }
+
+  protected buildExpression(match: RegExpMatchArray): PrimitiveExpression {
+    return this.builder(match);
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeDefinitions/EscapeDoubleQuotes.spec.ts

@@ -0,0 +1,33 @@
+import { describe } from 'vitest';
+import { EscapeDoubleQuotes } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeDefinitions/EscapeDoubleQuotes';
+import { getAbsentStringTestCases } from '@tests/unit/shared/TestCases/AbsentTests';
+import { runPipeTests } from './PipeTestRunner';
+
+describe('EscapeDoubleQuotes', () => {
+  // arrange
+  const sut = new EscapeDoubleQuotes();
+  // act
+  runPipeTests(sut, [
+    ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+      .map((testCase) => ({
+        name: 'returns as it is when if input is missing',
+        input: testCase.absentValue,
+        expectedOutput: testCase.absentValue,
+      })),
+    {
+      name: 'using "',
+      input: 'hello "world"',
+      expectedOutput: 'hello "^""world"^""',
+    },
+    {
+      name: 'not using any double quotes',
+      input: 'hello world',
+      expectedOutput: 'hello world',
+    },
+    {
+      name: 'consecutive double quotes',
+      input: '""hello world""',
+      expectedOutput: '"^"""^""hello world"^"""^""',
+    },
+  ]);
+});

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeDefinitions/InlinePowerShell.spec.ts

@@ -0,0 +1,465 @@
+import { describe } from 'vitest';
+import { InlinePowerShell } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeDefinitions/InlinePowerShell';
+import { getAbsentStringTestCases } from '@tests/unit/shared/TestCases/AbsentTests';
+import { type IPipeTestCase, runPipeTests } from './PipeTestRunner';
+
+describe('InlinePowerShell', () => {
+  // arrange
+  const sut = new InlinePowerShell();
+  // act
+  runPipeTests(sut, [
+    ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+      .map((testCase) => ({
+        name: 'returns as it is when if input is missing',
+        input: testCase.absentValue,
+        expectedOutput: '',
+      })),
+    ...prefixTests('newline', getNewLineCases()),
+    ...prefixTests('comment', getCommentCases()),
+    ...prefixTests('here-string', hereStringCases()),
+    ...prefixTests('backtick', backTickCases()),
+  ]);
+});
+
+function hereStringCases(): IPipeTestCase[] {
+  const expectLinesInDoubleQuotes = (...lines: string[]) => lines.join('`r`n');
+  const expectLinesInSingleQuotes = (...lines: string[]) => lines.join('\'+"`r`n"+\'');
+  return [
+    {
+      name: 'adds newlines for double quotes',
+      input: getWindowsLines(
+        '@"',
+        'Lorem',
+        'ipsum',
+        'dolor sit amet',
+        '"@',
+      ),
+      expectedOutput: expectLinesInDoubleQuotes(
+        '"Lorem',
+        'ipsum',
+        'dolor sit amet"',
+      ),
+    },
+    {
+      name: 'adds newlines for single quotes',
+      input: getWindowsLines(
+        '@\'',
+        'Lorem',
+        'ipsum',
+        'dolor sit amet',
+        '\'@',
+      ),
+      expectedOutput: expectLinesInSingleQuotes(
+        '\'Lorem',
+        'ipsum',
+        'dolor sit amet\'',
+      ),
+    },
+    {
+      name: 'does not match with character after here string header',
+      input: getWindowsLines(
+        '@" invalid syntax',
+        'I will not be processed as here-string',
+        '"@',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '@" invalid syntax',
+        'I will not be processed as here-string',
+        '"@',
+      ),
+    },
+    {
+      name: 'does not match if there\'s character before here-string terminator',
+      input: getWindowsLines(
+        '@\'',
+        'do not match here',
+        ' \'@',
+        'character \'@',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '@\'',
+        'do not match here',
+        ' \'@',
+        'character \'@',
+      ),
+    },
+    {
+      name: 'does not match with different here-string header/terminator',
+      input: getWindowsLines(
+        '@\'',
+        'lorem',
+        '"@',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '@\'',
+        'lorem',
+        '"@',
+      ),
+    },
+    {
+      name: 'matches with inner single quoted here-string',
+      input: getWindowsLines(
+        '$hasInnerDoubleQuotedTerminator = @"',
+        'inner text',
+        '@\'',
+        'inner terminator text',
+        '\'@',
+        '"@',
+      ),
+      expectedOutput: expectLinesInDoubleQuotes(
+        '$hasInnerDoubleQuotedTerminator = "inner text',
+        '@\'',
+        'inner terminator text',
+        '\'@"',
+      ),
+    },
+    {
+      name: 'matches with inner double quoted string',
+      input: getWindowsLines(
+        '$hasInnerSingleQuotedTerminator = @\'',
+        'inner text',
+        '@"',
+        'inner terminator text',
+        '"@',
+        '\'@',
+      ),
+      expectedOutput: expectLinesInSingleQuotes(
+        '$hasInnerSingleQuotedTerminator = \'inner text',
+        '@"',
+        'inner terminator text',
+        '"@\'',
+      ),
+    },
+    {
+      name: 'matches if there\'s character after here-string terminator',
+      input: getWindowsLines(
+        '@\'',
+        'lorem',
+        '\'@ after',
+      ),
+      expectedOutput: expectLinesInSingleQuotes(
+        '\'lorem\' after',
+      ),
+    },
+    {
+      name: 'escapes double quotes inside double quotes',
+      input: getWindowsLines(
+        '@"',
+        'For help, type "get-help"',
+        '"@',
+      ),
+      expectedOutput: '"For help, type `"get-help`""',
+    },
+    {
+      name: 'escapes single quotes inside single quotes',
+      input: getWindowsLines(
+        '@\'',
+        'For help, type \'get-help\'',
+        '\'@',
+      ),
+      expectedOutput: '\'For help, type \'\'get-help\'\'\'',
+    },
+    {
+      name: 'converts when here-string header is not at line start',
+      input: getWindowsLines(
+        '$page = [XML] @"',
+        'multi-lined',
+        'and "quoted"',
+        '"@',
+      ),
+      expectedOutput: expectLinesInDoubleQuotes(
+        '$page = [XML] "multi-lined',
+        'and `"quoted`""',
+      ),
+    },
+    {
+      name: 'trims after here-string header',
+      input: getWindowsLines(
+        '@"    \t',
+        'text with whitespaces at here-string start',
+        '"@',
+      ),
+      expectedOutput: '"text with whitespaces at here-string start"',
+    },
+    {
+      name: 'preserves whitespaces in lines',
+      input: getWindowsLines(
+        '@\'',
+        '\ttext with tabs around\t\t',
+        '  text with whitespaces around ',
+        '\'@',
+      ),
+      expectedOutput: expectLinesInSingleQuotes(
+        '\'\ttext with tabs around\t\t',
+        '  text with whitespaces around \'',
+      ),
+    },
+  ];
+}
+
+function backTickCases(): IPipeTestCase[] {
+  return [
+    {
+      name: 'wraps newlines with trailing backtick',
+      input: getWindowsLines(
+        'Get-Service * `',
+        '| Format-Table -AutoSize',
+      ),
+      expectedOutput: 'Get-Service * | Format-Table -AutoSize',
+    },
+    {
+      name: 'wraps newlines with trailing backtick and different line endings',
+      input: 'Get-Service `\n'
+        + '* `\r'
+        + '| Sort-Object StartType `\r\n'
+        + '| Format-Table -AutoSize',
+      expectedOutput: 'Get-Service * | Sort-Object StartType | Format-Table -AutoSize',
+    },
+    {
+      name: 'trims tabs and whitespaces on next lines when wrapping with trailing backtick',
+      input: getWindowsLines(
+        'Get-Service * `',
+        '\t| Sort-Object StartType `',
+        '  | Format-Table -AutoSize',
+      ),
+      expectedOutput: 'Get-Service * | Sort-Object StartType | Format-Table -AutoSize',
+    },
+    {
+      name: 'does not wrap without whitespace before backtick',
+      input: getWindowsLines(
+        'Get-Service *`',
+        '| Format-Table -AutoSize',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        'Get-Service *`',
+        '| Format-Table -AutoSize',
+      ),
+    },
+    {
+      name: 'does not wrap with characters after',
+      input: getWindowsLines(
+        'line start ` after',
+        'should not be wrapped',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        'line start ` after',
+        'should not be wrapped',
+      ),
+    },
+  ];
+}
+
+function getCommentCases(): IPipeTestCase[] {
+  return [
+    {
+      name: 'converts hash comments in the line end',
+      input: getWindowsLines(
+        '$text = "Hello"\t# Comment after tab',
+        '$text+= #Comment without space after hash',
+        'Write-Host $text# Comment without space before hash',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '$text = "Hello"\t<# Comment after tab #>',
+        '$text+= <# Comment without space after hash #>',
+        'Write-Host $text<# Comment without space before hash #>',
+      ),
+    },
+    {
+      name: 'converts hash comment line',
+      input: getWindowsLines(
+        '# Comment in first line',
+        'Write-Host "Hello"',
+        '# Comment in the middle',
+        'Write-Host "World"',
+        '# Consecutive comments',
+        '# Last line comment without line ending in the end',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '<# Comment in first line #>',
+        'Write-Host "Hello"',
+        '<# Comment in the middle #>',
+        'Write-Host "World"',
+        '<# Consecutive comments #>',
+        '<# Last line comment without line ending in the end #>',
+      ),
+    },
+    {
+      name: 'can convert comment with inline comment parts inside',
+      input: getWindowsLines(
+        '$text+= #Comment with < inside',
+        '$text+= #Comment ending with >',
+        '$text+= #Comment with <# inline comment #>',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '$text+= <# Comment with < inside #>',
+        '$text+= <# Comment ending with > #>',
+        '$text+= <# Comment with <# inline comment #> #>',
+      ),
+    },
+    {
+      name: 'can convert comment with inline comment parts around', // Pretty uncommon
+      input: getWindowsLines(
+        'Write-Host "hi" # Comment ending line inline comment but not one #>',
+        'Write-Host "hi" #>Comment starting like inline comment end but not one',
+        // Following line does not compile as valid PowerShell due to missing #> for inline comment.
+        'Write-Host "hi" <#Comment starting like inline comment start but not one',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        'Write-Host "hi" <# Comment ending line inline comment but not one #> #>',
+        'Write-Host "hi" <# >Comment starting like inline comment end but not one #>',
+        'Write-Host "hi" <<# Comment starting like inline comment start but not one #>',
+      ),
+    },
+    {
+      name: 'converts empty hash comment',
+      input: getWindowsLines(
+        'Write-Host "Comment without text" #',
+        'Write-Host "Non-empty line"',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        'Write-Host "Comment without text" <##>',
+        'Write-Host "Non-empty line"',
+      ),
+    },
+    {
+      name: 'adds whitespaces around to match',
+      input: getWindowsLines(
+        '#Comment line with no whitespaces around',
+        'Write-Host "Hello"#Comment in the end with no whitespaces around',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '<# Comment line with no whitespaces around #>',
+        'Write-Host "Hello"<# Comment in the end with no whitespaces around #>',
+      ),
+    },
+    {
+      name: 'trims whitespaces around comment',
+      input: getWindowsLines(
+        '#      Comment with whitespaces around       ',
+        '#\tComment with tabs around\t\t',
+        '#\t  Comment with tabs and whitespaces around  \t  \t',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '<# Comment with whitespaces around #>',
+        '<# Comment with tabs around #>',
+        '<# Comment with tabs and whitespaces around #>',
+      ),
+    },
+    {
+      name: 'does not convert block comments',
+      input: getWindowsLines(
+        '$text = "Hello"\t<# block comment #> + "World"',
+        '$text = "Hello"\t+<#comment#>"World"',
+        '<# Block comment in a line #>',
+        'Write-Host "Hello world <# Block comment in the end of line #>',
+      ),
+      expectedOutput: getSingleLinedOutput(
+        '$text = "Hello"\t<# block comment #> + "World"',
+        '$text = "Hello"\t+<#comment#>"World"',
+        '<# Block comment in a line #>',
+        'Write-Host "Hello world <# Block comment in the end of line #>',
+      ),
+    },
+    {
+      name: 'does not process if there are no multi lines',
+      input: 'Write-Host "expected" # as it is!',
+      expectedOutput: 'Write-Host "expected" # as it is!',
+    },
+  ];
+}
+
+function getNewLineCases(): IPipeTestCase[] {
+  return [
+    {
+      name: 'no new line',
+      input: 'Write-Host \'Hello, World!\'',
+      expectedOutput: 'Write-Host \'Hello, World!\'',
+    },
+    {
+      name: '\\n new line',
+      input:
+        '$things = Get-ChildItem C:\\Windows\\'
+          + '\nforeach ($thing in $things) {'
+          + '\nWrite-Host $thing.Name -ForegroundColor Magenta'
+          + '\n}',
+      expectedOutput: getSingleLinedOutput(
+        '$things = Get-ChildItem C:\\Windows\\',
+        'foreach ($thing in $things) {',
+        'Write-Host $thing.Name -ForegroundColor Magenta',
+        '}',
+      ),
+    },
+    {
+      name: '\\n double empty lines are ignored',
+      input:
+        '$things = Get-ChildItem C:\\Windows\\'
+          + '\n\nforeach ($thing in $things) {'
+          + '\n\nWrite-Host $thing.Name -ForegroundColor Magenta'
+          + '\n\n\n}',
+      expectedOutput: getSingleLinedOutput(
+        '$things = Get-ChildItem C:\\Windows\\',
+        'foreach ($thing in $things) {',
+        'Write-Host $thing.Name -ForegroundColor Magenta',
+        '}',
+      ),
+    },
+    {
+      name: '\\r new line',
+      input:
+        '$things = Get-ChildItem C:\\Windows\\'
+          + '\rforeach ($thing in $things) {'
+          + '\rWrite-Host $thing.Name -ForegroundColor Magenta'
+          + '\r}',
+      expectedOutput: getSingleLinedOutput(
+        '$things = Get-ChildItem C:\\Windows\\',
+        'foreach ($thing in $things) {',
+        'Write-Host $thing.Name -ForegroundColor Magenta',
+        '}',
+      ),
+    },
+    {
+      name: '\\r and \\n newlines combined',
+      input:
+        '$things = Get-ChildItem C:\\Windows\\'
+          + '\r\nforeach ($thing in $things) {'
+          + '\n\rWrite-Host $thing.Name -ForegroundColor Magenta'
+          + '\n\r}',
+      expectedOutput: getSingleLinedOutput(
+        '$things = Get-ChildItem C:\\Windows\\',
+        'foreach ($thing in $things) {',
+        'Write-Host $thing.Name -ForegroundColor Magenta',
+        '}',
+      ),
+    },
+    {
+      name: 'trims whitespaces on lines',
+      input:
+        ' $things = Get-ChildItem C:\\Windows\\   '
+          + '\nforeach ($thing in $things) {'
+          + '\n\tWrite-Host $thing.Name -ForegroundColor Magenta'
+          + '\r       \n}',
+      expectedOutput: getSingleLinedOutput(
+        '$things = Get-ChildItem C:\\Windows\\',
+        'foreach ($thing in $things) {',
+        'Write-Host $thing.Name -ForegroundColor Magenta',
+        '}',
+      ),
+    },
+  ];
+}
+
+function prefixTests(prefix: string, tests: IPipeTestCase[]): IPipeTestCase[] {
+  return tests.map((test) => ({
+    name: `[${prefix}] ${test.name}`,
+    input: test.input,
+    expectedOutput: test.expectedOutput,
+  }));
+}
+
+function getWindowsLines(...lines: string[]) {
+  return lines.join('\r\n');
+}
+
+function getSingleLinedOutput(...lines: string[]) {
+  return lines.map((line) => line.trim()).join('; ');
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeDefinitions/PipeTestRunner.ts

@@ -0,0 +1,19 @@
+import { it, expect } from 'vitest';
+import type { IPipe } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/IPipe';
+
+export interface IPipeTestCase {
+  readonly name: string;
+  readonly input: string;
+  readonly expectedOutput: string;
+}
+
+export function runPipeTests(sut: IPipe, testCases: IPipeTestCase[]) {
+  for (const testCase of testCases) {
+    it(testCase.name, () => {
+      // act
+      const actual = sut.apply(testCase.input);
+      // assert
+      expect(actual).to.equal(testCase.expectedOutput);
+    });
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeFactory.spec.ts

@@ -0,0 +1,95 @@
+import { describe, it, expect } from 'vitest';
+import { PipeFactory } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeFactory';
+import { PipeStub } from '@tests/unit/shared/Stubs/PipeStub';
+import { getAbsentStringTestCases } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('PipeFactory', () => {
+  describe('ctor', () => {
+    it('throws when instances with same name is registered', () => {
+      // arrange
+      const duplicateName = 'duplicateName';
+      const expectedError = `Pipe name must be unique: "${duplicateName}"`;
+      const pipes = [
+        new PipeStub().withName(duplicateName),
+        new PipeStub().withName('uniqueName'),
+        new PipeStub().withName(duplicateName),
+      ];
+      // act
+      const act = () => new PipeFactory(pipes);
+      // expect
+      expect(act).to.throw(expectedError);
+    });
+    describe('throws when name is invalid', () => {
+      // act
+      const act = (invalidName: string) => new PipeFactory([new PipeStub().withName(invalidName)]);
+      // assert
+      testPipeNameValidation(act);
+    });
+  });
+  describe('get', () => {
+    describe('throws when name is invalid', () => {
+      // arrange
+      const sut = new PipeFactory();
+      // act
+      const act = (invalidName: string) => sut.get(invalidName);
+      // assert
+      testPipeNameValidation(act);
+    });
+    it('gets registered instance when it exists', () => {
+      // arrange
+      const expected = new PipeStub().withName('expectedName');
+      const pipes = [expected, new PipeStub().withName('instanceToConfuse')];
+      const sut = new PipeFactory(pipes);
+      // act
+      const actual = sut.get(expected.name);
+      // expect
+      expect(actual).to.equal(expected);
+    });
+    it('throws when instance does not exist', () => {
+      // arrange
+      const missingName = 'missingName';
+      const expectedError = `Unknown pipe: "${missingName}"`;
+      const pipes = [];
+      const sut = new PipeFactory(pipes);
+      // act
+      const act = () => sut.get(missingName);
+      // expect
+      expect(act).to.throw(expectedError);
+    });
+  });
+});
+
+function testPipeNameValidation(testRunner: (invalidName: string) => void) {
+  const testCases = [
+    // Validate missing value
+    ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+      .map((testCase) => ({
+        name: `empty pipe name (${testCase.valueName})`,
+        value: testCase.absentValue,
+        expectedError: 'empty pipe name',
+      })),
+    // Validate camelCase
+    ...[
+      'PascalCase',
+      'snake-case',
+      'includesNumb3rs',
+      'includes Whitespace',
+      'noSpec\'ial',
+    ].map((nonCamelCaseValue) => ({
+      name: `non camel case value (${nonCamelCaseValue})`,
+      value: nonCamelCaseValue,
+      expectedError: `Pipe name should be camelCase: "${nonCamelCaseValue}"`,
+    })),
+  ];
+  for (const testCase of testCases) {
+    it(testCase.name, () => {
+      // arrange
+      const invalidName = testCase.value;
+      const { expectedError } = testCase;
+      // act
+      const act = () => testRunner(invalidName);
+      // expect
+      expect(act).to.throw(expectedError);
+    });
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipelineCompiler.spec.ts

@@ -0,0 +1,132 @@
+import { describe, it, expect } from 'vitest';
+import { PipelineCompiler } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipelineCompiler';
+import { type IPipelineCompiler } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/IPipelineCompiler';
+import type { IPipeFactory } from '@/application/Parser/Executable/Script/Compiler/Expressions/Pipes/PipeFactory';
+import { PipeStub } from '@tests/unit/shared/Stubs/PipeStub';
+import { PipeFactoryStub } from '@tests/unit/shared/Stubs/PipeFactoryStub';
+import { getAbsentStringTestCases } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('PipelineCompiler', () => {
+  describe('compile', () => {
+    describe('throws for invalid arguments', () => {
+      interface ITestCase {
+        readonly name: string;
+        readonly act: (test: PipelineTestRunner) => PipelineTestRunner;
+        readonly expectedError: string;
+      }
+      const testCases: ITestCase[] = [
+        ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+          .map((testCase) => ({
+            name: `"value" is ${testCase.valueName}`,
+            act: (test) => test.withValue(testCase.absentValue),
+            expectedError: 'missing value',
+          })),
+        ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+          .map((testCase) => ({
+            name: `"pipeline" is ${testCase.valueName}`,
+            act: (test) => test.withPipeline(testCase.absentValue),
+            expectedError: 'missing pipeline',
+          })),
+        {
+          name: '"pipeline" does not start with pipe',
+          act: (test) => test.withPipeline('pipeline |'),
+          expectedError: 'pipeline does not start with pipe',
+        },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.name, () => {
+          // act
+          const runner = new PipelineTestRunner();
+          testCase.act(runner);
+          const act = () => runner.compile();
+          // assert
+          expect(act).to.throw(testCase.expectedError);
+        });
+      }
+    });
+    describe('compiles pipeline as expected', () => {
+      const testCases = [
+        {
+          name: 'compiles single pipe as expected',
+          pipes: [
+            new PipeStub().withName('doublePrint').withApplier((value) => `${value}-${value}`),
+          ],
+          pipeline: '| doublePrint',
+          value: 'value',
+          expected: 'value-value',
+        },
+        {
+          name: 'compiles multiple pipes as expected',
+          pipes: [
+            new PipeStub().withName('prependLetterA').withApplier((value) => `A-${value}`),
+            new PipeStub().withName('prependLetterB').withApplier((value) => `B-${value}`),
+          ],
+          pipeline: '| prependLetterA | prependLetterB',
+          value: 'value',
+          expected: 'B-A-value',
+        },
+        {
+          name: 'compiles with relaxed whitespace placing',
+          pipes: [
+            new PipeStub().withName('appendNumberOne').withApplier((value) => `${value}1`),
+            new PipeStub().withName('appendNumberTwo').withApplier((value) => `${value}2`),
+            new PipeStub().withName('appendNumberThree').withApplier((value) => `${value}3`),
+          ],
+          pipeline: ' |      appendNumberOne|appendNumberTwo|   appendNumberThree',
+          value: 'value',
+          expected: 'value123',
+        },
+        {
+          name: 'can reuse same pipe',
+          pipes: [
+            new PipeStub().withName('removeFirstChar').withApplier((value) => `${value.slice(1)}`),
+          ],
+          pipeline: ' | removeFirstChar | removeFirstChar | removeFirstChar',
+          value: 'value',
+          expected: 'ue',
+        },
+      ];
+      for (const testCase of testCases) {
+        it(testCase.name, () => {
+          // arrange
+          const runner = new PipelineTestRunner()
+            .withValue(testCase.value)
+            .withPipeline(testCase.pipeline)
+            .withFactory(new PipeFactoryStub().withPipes(testCase.pipes));
+          // act
+          const actual = runner.compile();
+          // expect
+          expect(actual).to.equal(testCase.expected);
+        });
+      }
+    });
+  });
+});
+
+class PipelineTestRunner implements IPipelineCompiler {
+  private value = 'non-empty-value';
+
+  private pipeline = '| validPipeline';
+
+  private factory: IPipeFactory = new PipeFactoryStub();
+
+  public withValue(value: string) {
+    this.value = value;
+    return this;
+  }
+
+  public withPipeline(pipeline: string) {
+    this.pipeline = pipeline;
+    return this;
+  }
+
+  public withFactory(factory: IPipeFactory) {
+    this.factory = factory;
+    return this;
+  }
+
+  public compile(): string {
+    const sut = new PipelineCompiler(this.factory);
+    return sut.compile(this.value, this.pipeline);
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/SyntaxParsers/ParameterSubstitutionParser.spec.ts

@@ -0,0 +1,67 @@
+import { describe } from 'vitest';
+import { ParameterSubstitutionParser } from '@/application/Parser/Executable/Script/Compiler/Expressions/SyntaxParsers/ParameterSubstitutionParser';
+import { ExpressionPosition } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition';
+import { SyntaxParserTestsRunner } from './SyntaxParserTestsRunner';
+
+describe('ParameterSubstitutionParser', () => {
+  const sut = new ParameterSubstitutionParser();
+  const runner = new SyntaxParserTestsRunner(sut);
+  describe('finds as expected', () => {
+    runner.expectPosition(
+      {
+        name: 'single parameter',
+        code: '{{ $parameter }}!',
+        expected: [new ExpressionPosition(0, 16)],
+      },
+      {
+        name: 'different parameters',
+        code: 'He{{ $firstParameter }} {{ $secondParameter }}!!',
+        expected: [new ExpressionPosition(2, 23), new ExpressionPosition(24, 46)],
+      },
+      {
+        name: 'tolerates lack of spaces around brackets',
+        code: 'He{{$firstParameter}}!!',
+        expected: [new ExpressionPosition(2, 21)],
+      },
+      {
+        name: 'does not tolerate space after dollar sign',
+        code: 'He{{ $ firstParameter }}!!',
+        expected: [],
+      },
+    );
+  });
+  describe('evaluates as expected', () => {
+    runner.expectResults(
+      {
+        name: 'single parameter',
+        code: '{{ $parameter }}',
+        args: (args) => args
+          .withArgument('parameter', 'Hello world'),
+        expected: ['Hello world'],
+      },
+      {
+        name: 'different parameters',
+        code: '{{ $firstParameter }} {{ $secondParameter }}!',
+        args: (args) => args
+          .withArgument('firstParameter', 'Hello')
+          .withArgument('secondParameter', 'World'),
+        expected: ['Hello', 'World'],
+      },
+      {
+        name: 'same parameters used twice',
+        code: '{{ $letterH }}e{{ $letterL }}{{ $letterL }}o Wor{{ $letterL }}d!',
+        args: (args) => args
+          .withArgument('letterL', 'l')
+          .withArgument('letterH', 'H'),
+        expected: ['H', 'l', 'l', 'l'],
+      },
+    );
+  });
+  describe('compiles pipes as expected', () => {
+    runner.expectPipeHits({
+      codeBuilder: (pipeline) => `{{ $argument${pipeline}}}`,
+      parameterName: 'argument',
+      parameterValue: 'value',
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/SyntaxParsers/SyntaxParserTestsRunner.ts

@@ -0,0 +1,163 @@
+import { it, expect } from 'vitest';
+import { ExpressionPosition } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition';
+import type { IExpressionParser } from '@/application/Parser/Executable/Script/Compiler/Expressions/Parser/IExpressionParser';
+import { FunctionCallArgumentCollectionStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub';
+import { ExpressionEvaluationContextStub } from '@tests/unit/shared/Stubs/ExpressionEvaluationContextStub';
+import { PipelineCompilerStub } from '@tests/unit/shared/Stubs/PipelineCompilerStub';
+import { scrambledEqual } from '@/application/Common/Array';
+
+export class SyntaxParserTestsRunner {
+  constructor(private readonly sut: IExpressionParser) {
+  }
+
+  public expectPosition(...testCases: ExpectPositionTestScenario[]) {
+    for (const testCase of testCases) {
+      it(testCase.name, () => {
+        // act
+        const expressions = this.sut.findExpressions(testCase.code);
+        // assert
+        const actual = expressions.map((e) => e.position);
+        expect(scrambledEqual(actual, testCase.expected));
+      });
+    }
+    return this;
+  }
+
+  public expectNoMatch(...testCases: NoMatchTestScenario[]) {
+    this.expectPosition(...testCases.map((testCase) => ({
+      name: testCase.name,
+      code: testCase.code,
+      expected: [],
+    })));
+  }
+
+  public expectResults(...testCases: ExpectResultTestScenario[]) {
+    for (const testCase of testCases) {
+      it(testCase.name, () => {
+        // arrange
+        const args = testCase.args(new FunctionCallArgumentCollectionStub());
+        const context = new ExpressionEvaluationContextStub()
+          .withArgs(args);
+        // act
+        const expressions = this.sut.findExpressions(testCase.code);
+        // assert
+        const actual = expressions.map((e) => e.evaluate(context));
+        expect(actual).to.deep.equal(testCase.expected);
+      });
+    }
+    return this;
+  }
+
+  public expectThrows(...testCases: ExpectThrowsTestScenario[]) {
+    for (const testCase of testCases) {
+      it(testCase.name, () => {
+        // arrange
+        const { expectedError } = testCase;
+        // act
+        const act = () => this.sut.findExpressions(testCase.code);
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+    }
+    return this;
+  }
+
+  public expectPipeHits(data: ExpectPipeHitTestScenario) {
+    for (const validPipePart of PipeTestCases.ValidValues) {
+      this.expectHitPipePart(validPipePart, data);
+    }
+    for (const invalidPipePart of PipeTestCases.InvalidValues) {
+      this.expectMissPipePart(invalidPipePart, data);
+    }
+  }
+
+  private expectHitPipePart(pipeline: string, data: ExpectPipeHitTestScenario) {
+    it(`"${pipeline}" hits`, () => {
+      // arrange
+      const expectedPipePart = pipeline.trim();
+      const code = data.codeBuilder(pipeline);
+      const args = new FunctionCallArgumentCollectionStub()
+        .withArgument(data.parameterName, data.parameterValue);
+      const pipelineCompiler = new PipelineCompilerStub();
+      const context = new ExpressionEvaluationContextStub()
+        .withPipelineCompiler(pipelineCompiler)
+        .withArgs(args);
+      // act
+      const expressions = this.sut.findExpressions(code);
+      expressions[0].evaluate(context);
+      // assert
+      expect(expressions).has.lengthOf(1);
+      expect(pipelineCompiler.compileHistory).has.lengthOf(1);
+      const actualPipePart = pipelineCompiler.compileHistory[0].pipeline;
+      const actualValue = pipelineCompiler.compileHistory[0].value;
+      expect(actualPipePart).to.equal(expectedPipePart);
+      expect(actualValue).to.equal(data.parameterValue);
+    });
+  }
+
+  private expectMissPipePart(pipeline: string, data: ExpectPipeHitTestScenario) {
+    it(`"${pipeline}" misses`, () => {
+      // arrange
+      const args = new FunctionCallArgumentCollectionStub()
+        .withArgument(data.parameterName, data.parameterValue);
+      const pipelineCompiler = new PipelineCompilerStub();
+      const context = new ExpressionEvaluationContextStub()
+        .withPipelineCompiler(pipelineCompiler)
+        .withArgs(args);
+      const code = data.codeBuilder(pipeline);
+      // act
+      const expressions = this.sut.findExpressions(code);
+      expressions[0]?.evaluate(context); // Because an expression may include another with pipes
+      // assert
+      expect(pipelineCompiler.compileHistory).has.lengthOf(0);
+    });
+  }
+}
+
+interface ExpectResultTestScenario {
+  readonly name: string;
+  readonly code: string;
+  readonly args: (
+    builder: FunctionCallArgumentCollectionStub,
+  ) => FunctionCallArgumentCollectionStub;
+  readonly expected: readonly string[];
+}
+
+interface ExpectThrowsTestScenario {
+  readonly name: string;
+  readonly code: string;
+  readonly expectedError: string;
+}
+
+interface ExpectPositionTestScenario {
+  readonly name: string;
+  readonly code: string;
+  readonly expected: readonly ExpressionPosition[];
+}
+
+interface NoMatchTestScenario {
+  readonly name: string;
+  readonly code: string;
+}
+
+interface ExpectPipeHitTestScenario {
+  readonly codeBuilder: (pipeline: string) => string;
+  readonly parameterName: string;
+  readonly parameterValue: string;
+}
+
+const PipeTestCases = {
+  ValidValues: [
+    // Single pipe with different whitespace combinations
+    ' | pipe', ' |pipe', '|pipe', ' |pipe', '   |   pipe',
+
+    // Double pipes with different whitespace combinations
+    ' | pipeFirst | pipeSecond', '| pipeFirst|pipeSecond', '|pipeFirst|pipeSecond', ' |pipeFirst |pipeSecond', '| pipeFirst | pipeSecond| pipeThird |pipeFourth',
+  ],
+  InvalidValues: [
+    ' withoutPipeBefore  |pipe', ' withoutPipeBefore',
+
+    // It's OK to match them (move to valid values if needed) to let compiler throw instead.
+    '| pip€', '| pip{e} ', '| pipeWithNumber55', '| pipe with whitespace',
+  ],
+};

tests/unit/application/Parser/Executable/Script/Compiler/Expressions/SyntaxParsers/WithParser.spec.ts

@@ -0,0 +1,272 @@
+import { describe } from 'vitest';
+import { ExpressionPosition } from '@/application/Parser/Executable/Script/Compiler/Expressions/Expression/ExpressionPosition';
+import { WithParser } from '@/application/Parser/Executable/Script/Compiler/Expressions/SyntaxParsers/WithParser';
+import { getAbsentStringTestCases } from '@tests/unit/shared/TestCases/AbsentTests';
+import { SyntaxParserTestsRunner } from './SyntaxParserTestsRunner';
+
+describe('WithParser', () => {
+  const sut = new WithParser();
+  const runner = new SyntaxParserTestsRunner(sut);
+  describe('correctly identifies `with` syntax', () => {
+    runner.expectPosition(
+      {
+        name: 'when no context variable is not used',
+        code: 'hello {{ with $parameter }}no usage{{ end }} here',
+        expected: [new ExpressionPosition(6, 44)],
+      },
+      {
+        name: 'when context variable is used',
+        code: 'used here ({{ with $parameter }}value: {{.}}{{ end }})',
+        expected: [new ExpressionPosition(11, 53)],
+      },
+      {
+        name: 'when used twice',
+        code: 'first: {{ with $parameter }}value: {{ . }}{{ end }}, second: {{ with $parameter }}no usage{{ end }}',
+        expected: [new ExpressionPosition(7, 51), new ExpressionPosition(61, 99)],
+      },
+      {
+        name: 'when nested',
+        code: 'outer: {{ with $outer }}outer value with context variable: {{ . }}, inner: {{ with $inner }}inner value{{ end }}.{{ end }}',
+        expected: [
+          /* outer: */ new ExpressionPosition(7, 122),
+          /* inner: */ new ExpressionPosition(77, 112),
+        ],
+      },
+      {
+        name: 'whitespaces: tolerate lack of whitespaces',
+        code: 'no whitespaces {{with $parameter}}value: {{ . }}{{end}}',
+        expected: [new ExpressionPosition(15, 55)],
+      },
+      {
+        name: 'newlines: match multiline text',
+        code: 'non related line\n{{ with $middleLine }}\nline before value\n{{ . }}\nline after value\n{{ end }}\nnon related line',
+        expected: [new ExpressionPosition(17, 92)],
+      },
+      {
+        name: 'newlines: does not match newlines before',
+        code: '\n{{ with $unimportant }}Text{{ end }}',
+        expected: [new ExpressionPosition(1, 37)],
+      },
+      {
+        name: 'newlines: does not match newlines after',
+        code: '{{ with $unimportant }}Text{{ end }}\n',
+        expected: [new ExpressionPosition(0, 36)],
+      },
+    );
+  });
+  describe('throws with incorrect `with` syntax', () => {
+    runner.expectThrows(
+      {
+        name: 'incorrect `with`: whitespace after dollar sign inside `with` statement',
+        code: '{{with $ parameter}}value: {{ . }}{{ end }}',
+        expectedError: 'Context variable before `with` statement.',
+      },
+      {
+        name: 'incorrect `with`: whitespace before dollar sign inside `with` statement',
+        code: '{{ with$parameter}}value: {{ . }}{{ end }}',
+        expectedError: 'Context variable before `with` statement.',
+      },
+      {
+        name: 'incorrect `with`: missing `with` statement',
+        code: '{{ when $parameter}}value: {{ . }}{{ end }}',
+        expectedError: 'Context variable before `with` statement.',
+      },
+      {
+        name: 'incorrect `end`: missing `end` statement',
+        code: '{{ with $parameter}}value: {{ . }}{{ fin }}',
+        expectedError: 'Missing `end` statement, forgot `{{ end }}?',
+      },
+      {
+        name: 'incorrect `end`: used without `with`',
+        code: 'Value {{ end }}',
+        expectedError: 'Redundant `end` statement, missing `with`?',
+      },
+      {
+        name: 'incorrect "context variable": used without `with`',
+        code: 'Value: {{ . }}',
+        expectedError: 'Context variable before `with` statement.',
+      },
+    );
+  });
+  describe('ignores when syntax is wrong', () => {
+    describe('does not render argument if substitution syntax is wrong', () => {
+      runner.expectResults(
+        {
+          name: 'comma used instead of dot',
+          code: '{{ with $parameter }}Hello {{ , }}{{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'world!'),
+          expected: ['Hello {{ , }}'],
+        },
+        {
+          name: 'single brackets instead of double',
+          code: '{{ with $parameter }}Hello { . }{{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'world!'),
+          expected: ['Hello { . }'],
+        },
+        {
+          name: 'double dots instead of single',
+          code: '{{ with $parameter }}Hello {{ .. }}{{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'world!'),
+          expected: ['Hello {{ .. }}'],
+        },
+      );
+    });
+  });
+  describe('scope rendering', () => {
+    describe('conditional rendering based on argument value', () => {
+      describe('does not render scope', () => {
+        runner.expectResults(
+          ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+            .map((testCase) => ({
+              name: `does not render when value is "${testCase.valueName}"`,
+              code: '{{ with $parameter }}dark{{ end }} ',
+              args: (args) => args
+                .withArgument('parameter', testCase.absentValue),
+              expected: [''],
+            })),
+          {
+            name: 'does not render when argument is not provided',
+            code: '{{ with $parameter }}dark{{ end }}',
+            args: (args) => args,
+            expected: [''],
+          },
+        );
+      });
+      describe('renders scope', () => {
+        runner.expectResults(
+          ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+            .map((testCase) => ({
+              name: `does not render when value is "${testCase.valueName}"`,
+              code: '{{ with $parameter }}dark{{ end }} ',
+              args: (args) => args
+                .withArgument('parameter', testCase.absentValue),
+              expected: [''],
+            })),
+          {
+            name: 'does not render when argument is not provided',
+            code: '{{ with $parameter }}dark{{ end }}',
+            args: (args) => args,
+            expected: [''],
+          },
+          {
+            name: 'renders scope even if value is not used',
+            code: '{{ with $parameter }}Hello world!{{ end }}',
+            args: (args) => args
+              .withArgument('parameter', 'Hello'),
+            expected: ['Hello world!'],
+          },
+          {
+            name: 'renders value when it has value',
+            code: '{{ with $parameter }}{{ . }} world!{{ end }}',
+            args: (args) => args
+              .withArgument('parameter', 'Hello'),
+            expected: ['Hello world!'],
+          },
+          {
+            name: 'renders value when whitespaces around brackets are missing',
+            code: '{{ with $parameter }}{{.}} world!{{ end }}',
+            args: (args) => args
+              .withArgument('parameter', 'Hello'),
+            expected: ['Hello world!'],
+          },
+          {
+            name: 'renders value multiple times when it\'s used multiple times',
+            code: '{{ with $letterL }}He{{ . }}{{ . }}o wor{{ . }}d!{{ end }}',
+            args: (args) => args
+              .withArgument('letterL', 'l'),
+            expected: ['Hello world!'],
+          },
+        );
+      });
+    });
+    describe('whitespace handling inside scope', () => {
+      runner.expectResults(
+        {
+          name: 'renders value in multi-lined text',
+          code: '{{ with $middleLine }}line before value\n{{ . }}\nline after value{{ end }}',
+          args: (args) => args
+            .withArgument('middleLine', 'value line'),
+          expected: ['line before value\nvalue line\nline after value'],
+        },
+        {
+          name: 'renders value around whitespaces in multi-lined text',
+          code: '{{ with $middleLine }}\nline before value\n{{ . }}\nline after value\t {{ end }}',
+          args: (args) => args
+            .withArgument('middleLine', 'value line'),
+          expected: ['line before value\nvalue line\nline after value'],
+        },
+        {
+          name: 'does not render trailing whitespace after value',
+          code: '{{ with $parameter }}{{ . }}! {{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'Hello world'),
+          expected: ['Hello world!'],
+        },
+        {
+          name: 'does not render trailing newline after value',
+          code: '{{ with $parameter }}{{ . }}!\r\n{{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'Hello world'),
+          expected: ['Hello world!'],
+        },
+        {
+          name: 'does not render leading newline before value',
+          code: '{{ with $parameter }}\r\n{{ . }}!{{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'Hello world'),
+          expected: ['Hello world!'],
+        },
+        {
+          name: 'does not render leading whitespaces before value',
+          code: '{{ with $parameter }}  {{ . }}!{{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'Hello world'),
+          expected: ['Hello world!'],
+        },
+        {
+          name: 'does not render leading newline and whitespaces before value',
+          code: '{{ with $parameter }}\r\n  {{ . }}!{{ end }}',
+          args: (args) => args
+            .withArgument('parameter', 'Hello world'),
+          expected: ['Hello world!'],
+        },
+      );
+    });
+    describe('nested with statements', () => {
+      runner.expectResults(
+        {
+          name: 'renders nested with statements correctly',
+          code: '{{ with $outer }}Outer: {{ with $inner }}Inner: {{ . }}{{ end }}, Outer again: {{ . }}{{ end }}',
+          args: (args) => args
+            .withArgument('outer', 'OuterValue')
+            .withArgument('inner', 'InnerValue'),
+          expected: [
+            'Inner: InnerValue',
+            'Outer: {{ with $inner }}Inner: {{ . }}{{ end }}, Outer again: OuterValue',
+          ],
+        },
+        {
+          name: 'renders nested with statements with context variables',
+          code: '{{ with $outer }}{{ with $inner }}{{ . }}{{ . }}{{ end }}{{ . }}{{ end }}',
+          args: (args) => args
+            .withArgument('outer', 'O')
+            .withArgument('inner', 'I'),
+          expected: [
+            'II',
+            '{{ with $inner }}{{ . }}{{ . }}{{ end }}O',
+          ],
+        },
+      );
+    });
+  });
+  describe('pipe behavior', () => {
+    runner.expectPipeHits({
+      codeBuilder: (pipeline) => `{{ with $argument }} {{ .${pipeline}}} {{ end }}`,
+      parameterName: 'argument',
+      parameterValue: 'value',
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Argument/FunctionCallArgument.spec.ts

@@ -0,0 +1,52 @@
+import { describe, expect } from 'vitest';
+import { FunctionCallArgument } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Argument/FunctionCallArgument';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { testParameterName } from '../../../ParameterNameTestRunner';
+
+describe('FunctionCallArgument', () => {
+  describe('ctor', () => {
+    describe('parameter name', () => {
+      testParameterName(
+        (parameterName) => new FunctionCallArgumentBuilder()
+          .withParameterName(parameterName)
+          .build()
+          .parameterName,
+      );
+    });
+    describe('throws if argument value is absent', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const parameterName = 'paramName';
+        const expectedError = `Missing argument value for the parameter "${parameterName}".`;
+        const argumentValue = absentValue;
+        // act
+        const act = () => new FunctionCallArgumentBuilder()
+          .withParameterName(parameterName)
+          .withArgumentValue(argumentValue)
+          .build();
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+  });
+});
+
+class FunctionCallArgumentBuilder {
+  private parameterName = 'default-parameter-name';
+
+  private argumentValue = 'default-argument-value';
+
+  public withParameterName(parameterName: string) {
+    this.parameterName = parameterName;
+    return this;
+  }
+
+  public withArgumentValue(argumentValue: string) {
+    this.argumentValue = argumentValue;
+    return this;
+  }
+
+  public build() {
+    return new FunctionCallArgument(this.parameterName, this.argumentValue);
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Argument/FunctionCallArgumentCollection.spec.ts

@@ -0,0 +1,138 @@
+import { describe, it, expect } from 'vitest';
+import { FunctionCallArgumentCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Argument/FunctionCallArgumentCollection';
+import { FunctionCallArgumentStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentStub';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import type { IFunctionCallArgument } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Argument/IFunctionCallArgument';
+
+describe('FunctionCallArgumentCollection', () => {
+  describe('addArgument', () => {
+    it('throws if parameter value is already provided', () => {
+      // arrange
+      const duplicateParameterName = 'duplicateParam';
+      const errorMessage = `argument value for parameter ${duplicateParameterName} is already provided`;
+      const arg1 = new FunctionCallArgumentStub().withParameterName(duplicateParameterName);
+      const arg2 = new FunctionCallArgumentStub().withParameterName(duplicateParameterName);
+      const sut = new FunctionCallArgumentCollection();
+      // act
+      sut.addArgument(arg1);
+      const act = () => sut.addArgument(arg2);
+      // assert
+      expect(act).to.throw(errorMessage);
+    });
+  });
+  describe('getAllParameterNames', () => {
+    describe('returns as expected', () => {
+      // arrange
+      const testCases: ReadonlyArray<{
+        readonly description: string;
+        readonly args: readonly IFunctionCallArgument[];
+        readonly expectedParameterNames: string[];
+      }> = [{
+        description: 'no args',
+        args: [],
+        expectedParameterNames: [],
+      }, {
+        description: 'with some args',
+        args: [
+          new FunctionCallArgumentStub().withParameterName('a-param-name'),
+          new FunctionCallArgumentStub().withParameterName('b-param-name')],
+        expectedParameterNames: ['a-param-name', 'b-param-name'],
+      }];
+      for (const testCase of testCases) {
+        it(testCase.description, () => {
+          const sut = new FunctionCallArgumentCollection();
+          // act
+          for (const arg of testCase.args) {
+            sut.addArgument(arg);
+          }
+          const actual = sut.getAllParameterNames();
+          // assert
+          expect(actual).to.deep.equal(testCase.expectedParameterNames);
+        });
+      }
+    });
+  });
+  describe('getArgument', () => {
+    describe('throws if parameter name is absent', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const expectedError = 'missing parameter name';
+        const sut = new FunctionCallArgumentCollection();
+        const parameterName = absentValue;
+        // act
+        const act = () => sut.getArgument(parameterName);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+    it('throws if argument does not exist', () => {
+      // arrange
+      const parameterName = 'nonExistingParam';
+      const expectedError = `parameter does not exist: ${parameterName}`;
+      const sut = new FunctionCallArgumentCollection();
+      // act
+      const act = () => sut.getArgument(parameterName);
+      // assert
+      expect(act).to.throw(expectedError);
+    });
+    it('returns argument as expected', () => {
+      // arrange
+      const expected = new FunctionCallArgumentStub()
+        .withParameterName('expectedName')
+        .withArgumentValue('expectedValue');
+      const sut = new FunctionCallArgumentCollection();
+      // act
+      sut.addArgument(expected);
+      const actual = sut.getArgument(expected.parameterName);
+      // assert
+      expect(actual).to.equal(expected);
+    });
+  });
+  describe('hasArgument', () => {
+    describe('throws if parameter name is missing', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const expectedError = 'missing parameter name';
+        const parameterName = absentValue;
+        const sut = new FunctionCallArgumentCollection();
+        // act
+        const act = () => sut.hasArgument(parameterName);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+    describe('returns as expected', () => {
+      // arrange
+      const testCases = [{
+        name: 'argument exists',
+        parameter: 'existing-parameter-name',
+        args: [
+          new FunctionCallArgumentStub().withParameterName('existing-parameter-name'),
+          new FunctionCallArgumentStub().withParameterName('unrelated-parameter-name'),
+        ],
+        expected: true,
+      },
+      {
+        name: 'argument does not exist',
+        parameter: 'not-existing-parameter-name',
+        args: [
+          new FunctionCallArgumentStub().withParameterName('unrelated-parameter-name-b'),
+          new FunctionCallArgumentStub().withParameterName('unrelated-parameter-name-a'),
+        ],
+        expected: false,
+      }];
+      for (const testCase of testCases) {
+        it(`"${testCase.name}" returns "${testCase.expected}"`, () => {
+          const sut = new FunctionCallArgumentCollection();
+          // act
+          for (const arg of testCase.args) {
+            sut.addArgument(arg);
+          }
+          const actual = sut.hasArgument(testCase.parameter);
+          // assert
+          expect(actual).to.equal(testCase.expected);
+        });
+      }
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/CodeSegmentJoin/NewlineCodeSegmentMerger.spec.ts

@@ -0,0 +1,104 @@
+import { expect, describe, it } from 'vitest';
+import { NewlineCodeSegmentMerger } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/CodeSegmentJoin/NewlineCodeSegmentMerger';
+import { CompiledCodeStub } from '@tests/unit/shared/Stubs/CompiledCodeStub';
+import { getAbsentStringTestCases, itEachAbsentCollectionValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import type { CompiledCode } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/CompiledCode';
+
+describe('NewlineCodeSegmentMerger', () => {
+  describe('mergeCodeParts', () => {
+    describe('throws given empty segments', () => {
+      itEachAbsentCollectionValue<CompiledCode>((absentValue) => {
+        // arrange
+        const expectedError = 'missing segments';
+        const segments = absentValue;
+        const merger = new NewlineCodeSegmentMerger();
+        // act
+        const act = () => merger.mergeCodeParts(segments);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeUndefined: true, excludeNull: true });
+    });
+    describe('merges correctly', () => {
+      const testCases: ReadonlyArray<{
+        readonly description: string,
+        readonly segments: CompiledCodeStub[],
+        readonly expected: {
+          readonly code: string,
+          readonly revertCode?: string,
+        },
+      }> = [
+        {
+          description: 'given `code` and `revertCode`',
+          segments: [
+            new CompiledCodeStub().withCode('code1').withRevertCode('revert1'),
+            new CompiledCodeStub().withCode('code2').withRevertCode('revert2'),
+            new CompiledCodeStub().withCode('code3').withRevertCode('revert3'),
+          ],
+          expected: {
+            code: 'code1\ncode2\ncode3',
+            revertCode: 'revert1\nrevert2\nrevert3',
+          },
+        },
+        ...getAbsentStringTestCases({ excludeNull: true, excludeUndefined: true })
+          .map((absentTestCase) => ({
+            description: `filter out ${absentTestCase.valueName} \`revertCode\``,
+            segments: [
+              new CompiledCodeStub().withCode('code1').withRevertCode('revert1'),
+              new CompiledCodeStub().withCode('code2').withRevertCode(absentTestCase.absentValue),
+              new CompiledCodeStub().withCode('code3').withRevertCode('revert3'),
+            ],
+            expected: {
+              code: 'code1\ncode2\ncode3',
+              revertCode: 'revert1\nrevert3',
+            },
+          })),
+        ...getAbsentStringTestCases({ excludeNull: true })
+          .map((emptyRevertCode) => ({
+            description: `given only \`code\` in segments with "${emptyRevertCode.valueName}" \`revertCode\``,
+            segments: [
+              new CompiledCodeStub().withCode('code1').withRevertCode(emptyRevertCode.absentValue),
+              new CompiledCodeStub().withCode('code2').withRevertCode(emptyRevertCode.absentValue),
+            ],
+            expected: {
+              code: 'code1\ncode2',
+              revertCode: '',
+            },
+          })),
+        {
+          description: 'given mix of segments with only `code` or `revertCode`',
+          segments: [
+            new CompiledCodeStub().withCode('code1').withRevertCode(''),
+            new CompiledCodeStub().withCode('').withRevertCode('revert2'),
+            new CompiledCodeStub().withCode('code3').withRevertCode(''),
+          ],
+          expected: {
+            code: 'code1\ncode3',
+            revertCode: 'revert2',
+          },
+        },
+        {
+          description: 'given only `revertCode` in segments',
+          segments: [
+            new CompiledCodeStub().withCode('').withRevertCode('revert1'),
+            new CompiledCodeStub().withCode('').withRevertCode('revert2'),
+          ],
+          expected: {
+            code: '',
+            revertCode: 'revert1\nrevert2',
+          },
+        },
+      ];
+      for (const { segments, expected, description } of testCases) {
+        it(description, () => {
+          // arrange
+          const merger = new NewlineCodeSegmentMerger();
+          // act
+          const actual = merger.mergeCodeParts(segments);
+          // assert
+          expect(actual.code).to.equal(expected.code);
+          expect(actual.revertCode).to.equal(expected.revertCode);
+        });
+      }
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/FunctionCallSequenceCompiler.spec.ts

@@ -0,0 +1,223 @@
+/* eslint-disable max-classes-per-file */
+import { describe, it, expect } from 'vitest';
+import { FunctionCallSequenceCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/FunctionCallSequenceCompiler';
+import { itIsSingletonFactory } from '@tests/unit/shared/TestCases/SingletonFactoryTests';
+import { itEachAbsentCollectionValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import type { SingleCallCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/SingleCallCompiler';
+import type { CodeSegmentMerger } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/CodeSegmentJoin/CodeSegmentMerger';
+import type { ISharedFunctionCollection } from '@/application/Parser/Executable/Script/Compiler/Function/ISharedFunctionCollection';
+import type { FunctionCall } from '@/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCall';
+import { FunctionCallStub } from '@tests/unit/shared/Stubs/FunctionCallStub';
+import { SharedFunctionCollectionStub } from '@tests/unit/shared/Stubs/SharedFunctionCollectionStub';
+import { SingleCallCompilerStub } from '@tests/unit/shared/Stubs/SingleCallCompilerStub';
+import { CodeSegmentMergerStub } from '@tests/unit/shared/Stubs/CodeSegmentMergerStub';
+import { CompiledCodeStub } from '@tests/unit/shared/Stubs/CompiledCodeStub';
+import type { CompiledCode } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/CompiledCode';
+import { expectExists } from '@tests/shared/Assertions/ExpectExists';
+
+describe('FunctionCallSequenceCompiler', () => {
+  describe('instance', () => {
+    itIsSingletonFactory({
+      getter: () => FunctionCallSequenceCompiler.instance,
+      expectedType: FunctionCallSequenceCompiler,
+    });
+  });
+  describe('compileFunctionCalls', () => {
+    describe('parameter validation', () => {
+      describe('calls', () => {
+        describe('throws with missing call', () => {
+          itEachAbsentCollectionValue<FunctionCall>((absentValue) => {
+            // arrange
+            const expectedError = 'missing calls';
+            const calls = absentValue;
+            const builder = new FunctionCallSequenceCompilerBuilder()
+              .withCalls(calls);
+            // act
+            const act = () => builder.compileFunctionCalls();
+            // assert
+            expect(act).to.throw(expectedError);
+          }, { excludeUndefined: true, excludeNull: true });
+        });
+      });
+    });
+    describe('invokes single call compiler correctly', () => {
+      describe('calls', () => {
+        it('with expected call', () => {
+          // arrange
+          const singleCallCompilerStub = new SingleCallCompilerStub();
+          const expectedCall = new FunctionCallStub();
+          const builder = new FunctionCallSequenceCompilerBuilder()
+            .withSingleCallCompiler(singleCallCompilerStub)
+            .withCalls([expectedCall]);
+          // act
+          builder.compileFunctionCalls();
+          // assert
+          expect(singleCallCompilerStub.callHistory).to.have.lengthOf(1);
+          const calledMethod = singleCallCompilerStub.callHistory.find((m) => m.methodName === 'compileSingleCall');
+          expectExists(calledMethod);
+          expect(calledMethod.args[0]).to.equal(expectedCall);
+        });
+        it('with every call', () => {
+          // arrange
+          const singleCallCompilerStub = new SingleCallCompilerStub();
+          const expectedCalls = [
+            new FunctionCallStub(), new FunctionCallStub(), new FunctionCallStub(),
+          ];
+          const builder = new FunctionCallSequenceCompilerBuilder()
+            .withSingleCallCompiler(singleCallCompilerStub)
+            .withCalls(expectedCalls);
+          // act
+          builder.compileFunctionCalls();
+          // assert
+          const calledMethods = singleCallCompilerStub.callHistory.filter((m) => m.methodName === 'compileSingleCall');
+          expect(calledMethods).to.have.lengthOf(expectedCalls.length);
+          const callArguments = calledMethods.map((c) => c.args[0]);
+          expect(expectedCalls).to.have.members(callArguments);
+        });
+      });
+      describe('context', () => {
+        it('with expected functions', () => {
+          // arrange
+          const singleCallCompilerStub = new SingleCallCompilerStub();
+          const expectedFunctions = new SharedFunctionCollectionStub();
+          const builder = new FunctionCallSequenceCompilerBuilder()
+            .withSingleCallCompiler(singleCallCompilerStub)
+            .withFunctions(expectedFunctions);
+          // act
+          builder.compileFunctionCalls();
+          // assert
+          expect(singleCallCompilerStub.callHistory).to.have.lengthOf(1);
+          const calledMethod = singleCallCompilerStub.callHistory.find((m) => m.methodName === 'compileSingleCall');
+          expectExists(calledMethod);
+          const actualFunctions = calledMethod.args[1].allFunctions;
+          expect(actualFunctions).to.equal(expectedFunctions);
+        });
+        it('with expected call sequence', () => {
+          // arrange
+          const singleCallCompilerStub = new SingleCallCompilerStub();
+          const expectedCallSequence = [new FunctionCallStub(), new FunctionCallStub()];
+          const builder = new FunctionCallSequenceCompilerBuilder()
+            .withSingleCallCompiler(singleCallCompilerStub)
+            .withCalls(expectedCallSequence);
+          // act
+          builder.compileFunctionCalls();
+          // assert
+          const calledMethods = singleCallCompilerStub.callHistory.filter((m) => m.methodName === 'compileSingleCall');
+          expect(calledMethods).to.have.lengthOf(expectedCallSequence.length);
+          const calledSequenceArgs = calledMethods.map((call) => call.args[1].rootCallSequence);
+          expect(calledSequenceArgs.every((sequence) => sequence === expectedCallSequence));
+        });
+        it('with expected call compiler', () => {
+          // arrange
+          const expectedCompiler = new SingleCallCompilerStub();
+          const rootCallSequence = [new FunctionCallStub(), new FunctionCallStub()];
+          const builder = new FunctionCallSequenceCompilerBuilder()
+            .withCalls(rootCallSequence)
+            .withSingleCallCompiler(expectedCompiler);
+          // act
+          builder.compileFunctionCalls();
+          // assert
+          const calledMethods = expectedCompiler.callHistory.filter((m) => m.methodName === 'compileSingleCall');
+          expect(calledMethods).to.have.lengthOf(rootCallSequence.length);
+          const compilerArgs = calledMethods.map((call) => call.args[1].singleCallCompiler);
+          expect(compilerArgs.every((compiler) => compiler === expectedCompiler));
+        });
+      });
+    });
+    describe('code segment merger', () => {
+      it('invokes code segment merger correctly', () => {
+        // arrange
+        const singleCallCompilationScenario = new Map<FunctionCall, CompiledCode[]>([
+          [new FunctionCallStub(), [new CompiledCodeStub()]],
+          [new FunctionCallStub(), [new CompiledCodeStub(), new CompiledCodeStub()]],
+        ]);
+        const expectedFlattenedSegments = [...singleCallCompilationScenario.values()].flat();
+        const calls = [...singleCallCompilationScenario.keys()];
+        const singleCallCompiler = new SingleCallCompilerStub()
+          .withCallCompilationScenarios(singleCallCompilationScenario);
+        const codeSegmentMergerStub = new CodeSegmentMergerStub();
+        const builder = new FunctionCallSequenceCompilerBuilder()
+          .withCalls(calls)
+          .withSingleCallCompiler(singleCallCompiler)
+          .withCodeSegmentMerger(codeSegmentMergerStub);
+        // act
+        builder.compileFunctionCalls();
+        // assert
+        const calledMethod = codeSegmentMergerStub.callHistory.find((c) => c.methodName === 'mergeCodeParts');
+        expectExists(calledMethod);
+        const [actualSegments] = calledMethod.args;
+        expect(expectedFlattenedSegments).to.have.lengthOf(actualSegments.length);
+        expect(expectedFlattenedSegments).to.have.deep.members(actualSegments);
+      });
+      it('returns code segment merger result', () => {
+        // arrange
+        const expectedResult = new CompiledCodeStub();
+        const codeSegmentMergerStub = new CodeSegmentMergerStub();
+        codeSegmentMergerStub.mergeCodeParts = () => expectedResult;
+        const builder = new FunctionCallSequenceCompilerBuilder()
+          .withCodeSegmentMerger(codeSegmentMergerStub);
+        // act
+        const actualResult = builder.compileFunctionCalls();
+        // assert
+        expect(actualResult).to.equal(expectedResult);
+      });
+    });
+  });
+});
+
+class FunctionCallSequenceCompilerBuilder {
+  private singleCallCompiler: SingleCallCompiler = new SingleCallCompilerStub();
+
+  private codeSegmentMerger: CodeSegmentMerger = new CodeSegmentMergerStub();
+
+  private functions: ISharedFunctionCollection = new SharedFunctionCollectionStub();
+
+  private calls: readonly FunctionCall[] = [
+    new FunctionCallStub(),
+  ];
+
+  public withSingleCallCompiler(compiler: SingleCallCompiler): this {
+    this.singleCallCompiler = compiler;
+    return this;
+  }
+
+  public withCodeSegmentMerger(merger: CodeSegmentMerger): this {
+    this.codeSegmentMerger = merger;
+    return this;
+  }
+
+  public withCalls(calls: readonly FunctionCall[]): this {
+    this.calls = calls;
+    return this;
+  }
+
+  public withFunctions(functions: ISharedFunctionCollection): this {
+    this.functions = functions;
+    return this;
+  }
+
+  public compileFunctionCalls() {
+    const compiler = new TestableFunctionCallSequenceCompiler({
+      singleCallCompiler: this.singleCallCompiler,
+      codeSegmentMerger: this.codeSegmentMerger,
+    });
+    return compiler.compileFunctionCalls(
+      this.calls,
+      this.functions,
+    );
+  }
+}
+
+interface FunctionCallSequenceCompilerStubs {
+  readonly singleCallCompiler?: SingleCallCompiler;
+  readonly codeSegmentMerger: CodeSegmentMerger;
+}
+
+class TestableFunctionCallSequenceCompiler extends FunctionCallSequenceCompiler {
+  public constructor(options: FunctionCallSequenceCompilerStubs) {
+    super(
+      options.singleCallCompiler,
+      options.codeSegmentMerger,
+    );
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/NestedFunctionCallCompiler.spec.ts

@@ -0,0 +1,294 @@
+import { expect, describe, it } from 'vitest';
+import { createSharedFunctionStubWithCalls, createSharedFunctionStubWithCode } from '@tests/unit/shared/Stubs/SharedFunctionStub';
+import { NestedFunctionCallCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/NestedFunctionCallCompiler';
+import type { ArgumentCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/Argument/ArgumentCompiler';
+import { ArgumentCompilerStub } from '@tests/unit/shared/Stubs/ArgumentCompilerStub';
+import { FunctionCallStub } from '@tests/unit/shared/Stubs/FunctionCallStub';
+import { FunctionCallCompilationContextStub } from '@tests/unit/shared/Stubs/FunctionCallCompilationContextStub';
+import { SingleCallCompilerStub } from '@tests/unit/shared/Stubs/SingleCallCompilerStub';
+import { CompiledCodeStub } from '@tests/unit/shared/Stubs/CompiledCodeStub';
+import type { FunctionCall } from '@/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCall';
+import type { CompiledCode } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/CompiledCode';
+import { itThrowsContextualError } from '@tests/unit/application/Parser/ContextualErrorTester';
+import type { ErrorWithContextWrapper } from '@/application/Parser/ContextualError';
+import { errorWithContextWrapperStub } from '@tests/unit/shared/Stubs/ErrorWithContextWrapperStub';
+
+describe('NestedFunctionCallCompiler', () => {
+  describe('canCompile', () => {
+    it('returns `true` for code body function', () => {
+      // arrange
+      const expected = true;
+      const func = createSharedFunctionStubWithCalls()
+        .withSomeCalls();
+      const compiler = new NestedFunctionCallCompilerBuilder()
+        .build();
+      // act
+      const actual = compiler.canCompile(func);
+      // assert
+      expect(actual).to.equal(expected);
+    });
+    it('returns `false` for non-code body function', () => {
+      // arrange
+      const expected = false;
+      const func = createSharedFunctionStubWithCode();
+      const compiler = new NestedFunctionCallCompilerBuilder()
+        .build();
+      // act
+      const actual = compiler.canCompile(func);
+      // assert
+      expect(actual).to.equal(expected);
+    });
+  });
+  describe('compile', () => {
+    describe('argument compilation', () => {
+      it('uses correct context', () => {
+        // arrange
+        const argumentCompiler = new ArgumentCompilerStub();
+        const expectedContext = new FunctionCallCompilationContextStub();
+        const { frontFunction, callToFrontFunc } = createSingleFuncCallingAnotherFunc();
+        const compiler = new NestedFunctionCallCompilerBuilder()
+          .withArgumentCompiler(argumentCompiler)
+          .build();
+        // act
+        compiler.compileFunction(frontFunction, callToFrontFunc, expectedContext);
+        // assert
+        const calls = argumentCompiler.callHistory.filter((call) => call.methodName === 'createCompiledNestedCall');
+        expect(calls).have.lengthOf(1);
+        const [,,actualContext] = calls[0].args;
+        expect(actualContext).to.equal(expectedContext);
+      });
+      it('uses correct parent call', () => {
+        // arrange
+        const argumentCompiler = new ArgumentCompilerStub();
+        const expectedContext = new FunctionCallCompilationContextStub();
+        const { frontFunction, callToFrontFunc } = createSingleFuncCallingAnotherFunc();
+        const expectedParentCall = callToFrontFunc;
+        const compiler = new NestedFunctionCallCompilerBuilder()
+          .withArgumentCompiler(argumentCompiler)
+          .build();
+        // act
+        compiler.compileFunction(frontFunction, callToFrontFunc, expectedContext);
+        // assert
+        const calls = argumentCompiler.callHistory.filter((call) => call.methodName === 'createCompiledNestedCall');
+        expect(calls).have.lengthOf(1);
+        const [,actualParentCall] = calls[0].args;
+        expect(actualParentCall).to.equal(expectedParentCall);
+      });
+      it('uses correct nested call', () => {
+        // arrange
+        const argumentCompiler = new ArgumentCompilerStub();
+        const expectedContext = new FunctionCallCompilationContextStub();
+        const {
+          frontFunction, callToDeepFunc, callToFrontFunc,
+        } = createSingleFuncCallingAnotherFunc();
+        const expectedNestedCall = callToDeepFunc;
+        const compiler = new NestedFunctionCallCompilerBuilder()
+          .withArgumentCompiler(argumentCompiler)
+          .build();
+        // act
+        compiler.compileFunction(frontFunction, callToFrontFunc, expectedContext);
+        // assert
+        const calls = argumentCompiler.callHistory.filter((call) => call.methodName === 'createCompiledNestedCall');
+        expect(calls).have.lengthOf(1);
+        const [actualNestedCall] = calls[0].args;
+        expect(actualNestedCall).to.deep.equal(expectedNestedCall);
+      });
+    });
+    describe('re-compilation with compiled args', () => {
+      it('uses correct context', () => {
+        // arrange
+        const singleCallCompilerStub = new SingleCallCompilerStub();
+        const expectedContext = new FunctionCallCompilationContextStub()
+          .withSingleCallCompiler(singleCallCompilerStub);
+        const { frontFunction, callToFrontFunc } = createSingleFuncCallingAnotherFunc();
+        const compiler = new NestedFunctionCallCompilerBuilder()
+          .build();
+        // act
+        compiler.compileFunction(frontFunction, callToFrontFunc, expectedContext);
+        // assert
+        const calls = singleCallCompilerStub.callHistory.filter((call) => call.methodName === 'compileSingleCall');
+        expect(calls).have.lengthOf(1);
+        const [,actualContext] = calls[0].args;
+        expect(expectedContext).to.equal(actualContext);
+      });
+      it('uses compiled nested call', () => {
+        // arrange
+        const expectedCall = new FunctionCallStub();
+        const argumentCompilerStub = new ArgumentCompilerStub();
+        argumentCompilerStub.createCompiledNestedCall = () => expectedCall;
+        const singleCallCompilerStub = new SingleCallCompilerStub();
+        const context = new FunctionCallCompilationContextStub()
+          .withSingleCallCompiler(singleCallCompilerStub);
+        const { frontFunction, callToFrontFunc } = createSingleFuncCallingAnotherFunc();
+        const compiler = new NestedFunctionCallCompilerBuilder()
+          .withArgumentCompiler(argumentCompilerStub)
+          .build();
+        // act
+        compiler.compileFunction(frontFunction, callToFrontFunc, context);
+        // assert
+        const calls = singleCallCompilerStub.callHistory.filter((call) => call.methodName === 'compileSingleCall');
+        expect(calls).have.lengthOf(1);
+        const [actualNestedCall] = calls[0].args;
+        expect(expectedCall).to.equal(actualNestedCall);
+      });
+    });
+    it('flattens re-compiled functions', () => {
+      // arrange
+      const deepFunc1 = createSharedFunctionStubWithCode();
+      const deepFunc2 = createSharedFunctionStubWithCalls();
+      const callToDeepFunc1 = new FunctionCallStub().withFunctionName(deepFunc1.name);
+      const callToDeepFunc2 = new FunctionCallStub().withFunctionName(deepFunc2.name);
+      const singleCallCompilationScenario = new Map<FunctionCall, CompiledCode[]>([
+        [callToDeepFunc1, [new CompiledCodeStub()]],
+        [callToDeepFunc2, [new CompiledCodeStub(), new CompiledCodeStub()]],
+      ]);
+      const argumentCompiler = new ArgumentCompilerStub()
+        .withScenario({ givenNestedFunctionCall: callToDeepFunc1, result: callToDeepFunc1 })
+        .withScenario({ givenNestedFunctionCall: callToDeepFunc2, result: callToDeepFunc2 });
+      const expectedFlattenedCodes = [...singleCallCompilationScenario.values()].flat();
+      const frontFunction = createSharedFunctionStubWithCalls()
+        .withCalls(callToDeepFunc1, callToDeepFunc2);
+      const callToFrontFunc = new FunctionCallStub().withFunctionName(frontFunction.name);
+      const singleCallCompilerStub = new SingleCallCompilerStub()
+        .withCallCompilationScenarios(singleCallCompilationScenario);
+      const expectedContext = new FunctionCallCompilationContextStub()
+        .withSingleCallCompiler(singleCallCompilerStub);
+      const compiler = new NestedFunctionCallCompilerBuilder()
+        .withArgumentCompiler(argumentCompiler)
+        .build();
+      // act
+      const actualCodes = compiler.compileFunction(frontFunction, callToFrontFunc, expectedContext);
+      // assert
+      expect(actualCodes).have.lengthOf(expectedFlattenedCodes.length);
+      expect(actualCodes).to.have.members(expectedFlattenedCodes);
+    });
+    describe('error handling', () => {
+      describe('rethrows error from argument compiler', () => {
+        // arrange
+        const expectedInnerError = new Error(`Expected error from ${ArgumentCompilerStub.name}`);
+        const calleeFunctionName = 'expectedCalleeFunctionName';
+        const callerFunctionName = 'expectedCallerFunctionName';
+        const expectedErrorMessage = buildRethrowErrorMessage({
+          callee: calleeFunctionName,
+          caller: callerFunctionName,
+        });
+        const { frontFunction, callToFrontFunc } = createSingleFuncCallingAnotherFunc({
+          frontFunctionName: callerFunctionName,
+          deepFunctionName: calleeFunctionName,
+        });
+        const argumentCompilerStub = new ArgumentCompilerStub();
+        argumentCompilerStub.createCompiledNestedCall = () => {
+          throw expectedInnerError;
+        };
+        const builder = new NestedFunctionCallCompilerBuilder()
+          .withArgumentCompiler(argumentCompilerStub);
+        itThrowsContextualError({
+          // act
+          throwingAction: (wrapError) => {
+            builder
+              .withErrorWrapper(wrapError)
+              .build()
+              .compileFunction(
+                frontFunction,
+                callToFrontFunc,
+                new FunctionCallCompilationContextStub(),
+              );
+          },
+          // assert
+          expectedWrappedError: expectedInnerError,
+          expectedContextMessage: expectedErrorMessage,
+        });
+      });
+      describe('rethrows error from single call compiler', () => {
+        // arrange
+        const expectedInnerError = new Error(`Expected error from ${SingleCallCompilerStub.name}`);
+        const calleeFunctionName = 'expectedCalleeFunctionName';
+        const callerFunctionName = 'expectedCallerFunctionName';
+        const expectedErrorMessage = buildRethrowErrorMessage({
+          callee: calleeFunctionName,
+          caller: callerFunctionName,
+        });
+        const { frontFunction, callToFrontFunc } = createSingleFuncCallingAnotherFunc({
+          frontFunctionName: callerFunctionName,
+          deepFunctionName: calleeFunctionName,
+        });
+        const singleCallCompiler = new SingleCallCompilerStub();
+        singleCallCompiler.compileSingleCall = () => {
+          throw expectedInnerError;
+        };
+        const context = new FunctionCallCompilationContextStub()
+          .withSingleCallCompiler(singleCallCompiler);
+        const builder = new NestedFunctionCallCompilerBuilder();
+        itThrowsContextualError({
+          // act
+          throwingAction: (wrapError) => {
+            builder
+              .withErrorWrapper(wrapError)
+              .build()
+              .compileFunction(
+                frontFunction,
+                callToFrontFunc,
+                context,
+              );
+          },
+          // assert
+          expectedWrappedError: expectedInnerError,
+          expectedContextMessage: expectedErrorMessage,
+        });
+      });
+    });
+  });
+});
+
+function createSingleFuncCallingAnotherFunc(
+  functionNames?: {
+    readonly frontFunctionName?: string;
+    readonly deepFunctionName?: string;
+  },
+) {
+  const deepFunction = createSharedFunctionStubWithCode()
+    .withName(functionNames?.deepFunctionName ?? 'deep-function (is called by front-function)');
+  const callToDeepFunc = new FunctionCallStub().withFunctionName(deepFunction.name);
+  const frontFunction = createSharedFunctionStubWithCalls()
+    .withCalls(callToDeepFunc)
+    .withName(functionNames?.frontFunctionName ?? 'front-function (calls deep-function)');
+  const callToFrontFunc = new FunctionCallStub().withFunctionName(frontFunction.name);
+  return {
+    deepFunction,
+    frontFunction,
+    callToFrontFunc,
+    callToDeepFunc,
+  };
+}
+
+class NestedFunctionCallCompilerBuilder {
+  private argumentCompiler: ArgumentCompiler = new ArgumentCompilerStub();
+
+  private wrapError: ErrorWithContextWrapper = errorWithContextWrapperStub;
+
+  public withArgumentCompiler(argumentCompiler: ArgumentCompiler): this {
+    this.argumentCompiler = argumentCompiler;
+    return this;
+  }
+
+  public withErrorWrapper(wrapError: ErrorWithContextWrapper): this {
+    this.wrapError = wrapError;
+    return this;
+  }
+
+  public build(): NestedFunctionCallCompiler {
+    return new NestedFunctionCallCompiler(
+      this.argumentCompiler,
+      this.wrapError,
+    );
+  }
+}
+
+function buildRethrowErrorMessage(
+  functionNames: {
+    readonly caller: string;
+    readonly callee: string;
+  },
+) {
+  return `Failed to call '${functionNames.callee}' (callee function) from '${functionNames.caller}' (caller function).`;
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/AdaptiveFunctionCallCompiler.spec.ts

@@ -0,0 +1,260 @@
+import { expect, describe, it } from 'vitest';
+import { createSharedFunctionStubWithCode } from '@tests/unit/shared/Stubs/SharedFunctionStub';
+import type { FunctionCallParametersData } from '@/application/collections/';
+import { FunctionCallStub } from '@tests/unit/shared/Stubs/FunctionCallStub';
+import { SharedFunctionCollectionStub } from '@tests/unit/shared/Stubs/SharedFunctionCollectionStub';
+import { AdaptiveFunctionCallCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/AdaptiveFunctionCallCompiler';
+import type { SingleCallCompilerStrategy } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/SingleCallCompilerStrategy';
+import { SingleCallCompilerStrategyStub } from '@tests/unit/shared/Stubs/SingleCallCompilerStrategyStub';
+import type { FunctionCall } from '@/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCall';
+import type { FunctionCallCompilationContext } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/FunctionCallCompilationContext';
+import { FunctionCallCompilationContextStub } from '@tests/unit/shared/Stubs/FunctionCallCompilationContextStub';
+import { CompiledCodeStub } from '@tests/unit/shared/Stubs/CompiledCodeStub';
+import type { SingleCallCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/SingleCallCompiler';
+import { collectExceptionMessage } from '@tests/unit/shared/ExceptionCollector';
+
+describe('AdaptiveFunctionCallCompiler', () => {
+  describe('compileSingleCall', () => {
+    describe('throws if call parameters does not match function parameters', () => {
+      // arrange
+      const functionName = 'test-function-name';
+      const testCases: Array<{
+        readonly description: string,
+        readonly functionParameters: string[],
+        readonly callParameters: string[]
+        readonly expectedError: string;
+      }> = [
+        {
+          description: 'provided: single unexpected parameter, when: another expected',
+          functionParameters: ['expected-parameter'],
+          callParameters: ['unexpected-parameter'],
+          expectedError:
+            `Function "${functionName}" has unexpected parameter(s) provided: "unexpected-parameter".`
+            + '\nExpected parameter(s): "expected-parameter"',
+        },
+        {
+          description: 'provided: multiple unexpected parameters, when: different one is expected',
+          functionParameters: ['expected-parameter'],
+          callParameters: ['unexpected-parameter1', 'unexpected-parameter2'],
+          expectedError:
+            `Function "${functionName}" has unexpected parameter(s) provided: "unexpected-parameter1", "unexpected-parameter2".`
+            + '\nExpected parameter(s): "expected-parameter"',
+        },
+        {
+          description: 'provided: an unexpected parameter, when: multiple parameters are expected',
+          functionParameters: ['expected-parameter1', 'expected-parameter2'],
+          callParameters: ['expected-parameter1', 'expected-parameter2', 'unexpected-parameter'],
+          expectedError:
+            `Function "${functionName}" has unexpected parameter(s) provided: "unexpected-parameter".`
+            + '\nExpected parameter(s): "expected-parameter1", "expected-parameter2"',
+        },
+        {
+          description: 'provided: an unexpected parameter, when: none required',
+          functionParameters: [],
+          callParameters: ['unexpected-call-parameter'],
+          expectedError:
+            `Function "${functionName}" has unexpected parameter(s) provided: "unexpected-call-parameter".`
+            + '\nExpected parameter(s): none',
+        },
+        {
+          description: 'provided: expected and unexpected parameter, when: one of them is expected',
+          functionParameters: ['expected-parameter'],
+          callParameters: ['expected-parameter', 'unexpected-parameter'],
+          expectedError:
+            `Function "${functionName}" has unexpected parameter(s) provided: "unexpected-parameter".`
+            + '\nExpected parameter(s): "expected-parameter"',
+        },
+      ];
+      testCases.forEach(({
+        description, functionParameters, callParameters, expectedError,
+      }) => {
+        it(description, () => {
+          // arrange
+          const func = createSharedFunctionStubWithCode()
+            .withName('test-function-name')
+            .withParameterNames(...functionParameters);
+          const params = callParameters
+            .reduce((result, parameter) => {
+              return { ...result, [parameter]: 'defined-parameter-value' };
+            }, {} as FunctionCallParametersData);
+          const call = new FunctionCallStub()
+            .withFunctionName(func.name)
+            .withArguments(params);
+          const builder = new AdaptiveFunctionCallCompilerBuilder()
+            .withContext(new FunctionCallCompilationContextStub()
+              .withAllFunctions(
+                new SharedFunctionCollectionStub().withFunctions(func),
+              ))
+            .withCall(call);
+          // act
+          const act = () => builder.compileSingleCall();
+          // assert
+          const errorMessage = collectExceptionMessage(act);
+          expect(errorMessage).to.include(expectedError);
+        });
+      });
+    });
+    describe('strategy selection', () => {
+      it('uses the matching strategy among multiple', () => {
+        // arrange
+        const matchedStrategy = new SingleCallCompilerStrategyStub()
+          .withCanCompileResult(true);
+        const unmatchedStrategy = new SingleCallCompilerStrategyStub()
+          .withCanCompileResult(false);
+        const builder = new AdaptiveFunctionCallCompilerBuilder()
+          .withStrategies([matchedStrategy, unmatchedStrategy]);
+        // act
+        builder.compileSingleCall();
+        // assert
+        expect(matchedStrategy.callHistory.filter((c) => c.methodName === 'compileFunction')).to.have.lengthOf(1);
+        expect(unmatchedStrategy.callHistory.filter((c) => c.methodName === 'compileFunction')).to.have.lengthOf(0);
+      });
+      it('throws if multiple strategies can compile', () => {
+        // arrange
+        const expectedError = 'Multiple strategies found to compile the function call.';
+        const matchedStrategy1 = new SingleCallCompilerStrategyStub().withCanCompileResult(true);
+        const matchedStrategy2 = new SingleCallCompilerStrategyStub().withCanCompileResult(true);
+        const builder = new AdaptiveFunctionCallCompilerBuilder().withStrategies(
+          [matchedStrategy1, matchedStrategy2],
+        );
+        // act
+        const act = () => builder.compileSingleCall();
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+      it('throws if no strategy can compile', () => {
+        // arrange
+        const expectedError = 'No strategies found to compile the function call.';
+        const unmatchedStrategy = new SingleCallCompilerStrategyStub()
+          .withCanCompileResult(false);
+        const builder = new AdaptiveFunctionCallCompilerBuilder()
+          .withStrategies([unmatchedStrategy]);
+        // act
+        const act = () => builder.compileSingleCall();
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+    });
+    describe('strategy invocation', () => {
+      it('passes correct function for compilation ability check', () => {
+        // arrange
+        const expectedFunction = createSharedFunctionStubWithCode();
+        const strategy = new SingleCallCompilerStrategyStub()
+          .withCanCompileResult(true);
+        const builder = new AdaptiveFunctionCallCompilerBuilder()
+          .withContext(new FunctionCallCompilationContextStub()
+            .withAllFunctions(
+              new SharedFunctionCollectionStub().withFunctions(expectedFunction),
+            ))
+          .withCall(new FunctionCallStub().withFunctionName(expectedFunction.name))
+          .withStrategies([strategy]);
+        // act
+        builder.compileSingleCall();
+        // assert
+        const call = strategy.callHistory.filter((c) => c.methodName === 'canCompile');
+        expect(call).to.have.lengthOf(1);
+        expect(call[0].args[0]).to.equal(expectedFunction);
+      });
+      describe('compilation arguments', () => {
+        it('uses correct function', () => {
+          // arrange
+          const expectedFunction = createSharedFunctionStubWithCode();
+          const strategy = new SingleCallCompilerStrategyStub()
+            .withCanCompileResult(true);
+          const builder = new AdaptiveFunctionCallCompilerBuilder()
+            .withContext(new FunctionCallCompilationContextStub()
+              .withAllFunctions(
+                new SharedFunctionCollectionStub().withFunctions(expectedFunction),
+              ))
+            .withCall(new FunctionCallStub().withFunctionName(expectedFunction.name))
+            .withStrategies([strategy]);
+          // act
+          builder.compileSingleCall();
+          // assert
+          const call = strategy.callHistory.filter((c) => c.methodName === 'compileFunction');
+          expect(call).to.have.lengthOf(1);
+          const [actualFunction] = call[0].args;
+          expect(actualFunction).to.equal(expectedFunction);
+        });
+        it('uses correct call', () => {
+          // arrange
+          const expectedCall = new FunctionCallStub();
+          const strategy = new SingleCallCompilerStrategyStub()
+            .withCanCompileResult(true);
+          const builder = new AdaptiveFunctionCallCompilerBuilder()
+            .withStrategies([strategy])
+            .withCall(expectedCall);
+          // act
+          builder.compileSingleCall();
+          // assert
+          const call = strategy.callHistory.filter((c) => c.methodName === 'compileFunction');
+          expect(call).to.have.lengthOf(1);
+          const [,actualCall] = call[0].args;
+          expect(actualCall).to.equal(expectedCall);
+        });
+        it('uses correct context', () => {
+          // arrange
+          const expectedContext = new FunctionCallCompilationContextStub();
+          const strategy = new SingleCallCompilerStrategyStub()
+            .withCanCompileResult(true);
+          const builder = new AdaptiveFunctionCallCompilerBuilder()
+            .withStrategies([strategy])
+            .withContext(expectedContext);
+          // act
+          builder.compileSingleCall();
+          // assert
+          const call = strategy.callHistory.filter((c) => c.methodName === 'compileFunction');
+          expect(call).to.have.lengthOf(1);
+          const [,,actualContext] = call[0].args;
+          expect(actualContext).to.equal(expectedContext);
+        });
+      });
+    });
+    it('returns compiled code from strategy', () => {
+      // arrange
+      const expectedResult = [new CompiledCodeStub(), new CompiledCodeStub()];
+      const strategy = new SingleCallCompilerStrategyStub()
+        .withCanCompileResult(true)
+        .withCompiledFunctionResult(expectedResult);
+      const builder = new AdaptiveFunctionCallCompilerBuilder()
+        .withStrategies([strategy]);
+      // act
+      const actualResult = builder.compileSingleCall();
+      // assert
+      expect(expectedResult).to.equal(actualResult);
+    });
+  });
+});
+
+class AdaptiveFunctionCallCompilerBuilder implements SingleCallCompiler {
+  private strategies: SingleCallCompilerStrategy[] = [
+    new SingleCallCompilerStrategyStub().withCanCompileResult(true),
+  ];
+
+  private call: FunctionCall = new FunctionCallStub();
+
+  private context: FunctionCallCompilationContext = new FunctionCallCompilationContextStub();
+
+  public withCall(call: FunctionCall): this {
+    this.call = call;
+    return this;
+  }
+
+  public withContext(context: FunctionCallCompilationContext): this {
+    this.context = context;
+    return this;
+  }
+
+  public withStrategies(strategies: SingleCallCompilerStrategy[]): this {
+    this.strategies = strategies;
+    return this;
+  }
+
+  public compileSingleCall() {
+    const compiler = new AdaptiveFunctionCallCompiler(this.strategies);
+    return compiler.compileSingleCall(
+      this.call,
+      this.context,
+    );
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/Argument/NestedFunctionArgumentCompiler.spec.ts

@@ -0,0 +1,305 @@
+import { expect, describe, it } from 'vitest';
+import type { ArgumentCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/Argument/ArgumentCompiler';
+import type { FunctionCallCompilationContext } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/FunctionCallCompilationContext';
+import type { FunctionCall } from '@/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCall';
+import { NestedFunctionArgumentCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/Argument/NestedFunctionArgumentCompiler';
+import type { IExpressionsCompiler } from '@/application/Parser/Executable/Script/Compiler/Expressions/IExpressionsCompiler';
+import { ExpressionsCompilerStub } from '@tests/unit/shared/Stubs/ExpressionsCompilerStub';
+import { FunctionCallCompilationContextStub } from '@tests/unit/shared/Stubs/FunctionCallCompilationContextStub';
+import { FunctionCallStub } from '@tests/unit/shared/Stubs/FunctionCallStub';
+import { FunctionCallArgumentCollectionStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub';
+import { createSharedFunctionStubWithCode } from '@tests/unit/shared/Stubs/SharedFunctionStub';
+import { FunctionParameterCollectionStub } from '@tests/unit/shared/Stubs/FunctionParameterCollectionStub';
+import { SharedFunctionCollectionStub } from '@tests/unit/shared/Stubs/SharedFunctionCollectionStub';
+import { itThrowsContextualError } from '@tests/unit/application/Parser/ContextualErrorTester';
+import type { ErrorWithContextWrapper } from '@/application/Parser/ContextualError';
+import { errorWithContextWrapperStub } from '@tests/unit/shared/Stubs/ErrorWithContextWrapperStub';
+
+describe('NestedFunctionArgumentCompiler', () => {
+  describe('createCompiledNestedCall', () => {
+    describe('rethrows error from expressions compiler', () => {
+      // arrange
+      const expectedInnerError = new Error('child-');
+      const parameterName = 'parameterName';
+      const expectedErrorMessage = `Error when compiling argument for "${parameterName}"`;
+      const nestedCall = new FunctionCallStub()
+        .withFunctionName('nested-function-call')
+        .withArgumentCollection(new FunctionCallArgumentCollectionStub()
+          .withArgument(parameterName, 'unimportant-value'));
+      const parentCall = new FunctionCallStub()
+        .withFunctionName('parent-function-call');
+      const expressionsCompiler = new ExpressionsCompilerStub();
+      expressionsCompiler.compileExpressions = () => { throw expectedInnerError; };
+      const builder = new NestedFunctionArgumentCompilerBuilder()
+        .withParentFunctionCall(parentCall)
+        .withNestedFunctionCall(nestedCall)
+        .withExpressionsCompiler(expressionsCompiler);
+      itThrowsContextualError({
+        // act
+        throwingAction: (wrapError) => {
+          builder
+            .withErrorWrapper(wrapError)
+            .createCompiledNestedCall();
+        },
+        // assert
+        expectedWrappedError: expectedInnerError,
+        expectedContextMessage: expectedErrorMessage,
+      });
+    });
+    describe('compilation', () => {
+      describe('without arguments', () => {
+        it('matches nested call name', () => {
+          // arrange
+          const expectedCall = new FunctionCallStub()
+            .withArgumentCollection(new FunctionCallArgumentCollectionStub().withEmptyArguments());
+          const builder = new NestedFunctionArgumentCompilerBuilder()
+            .withNestedFunctionCall(expectedCall);
+          // act
+          const actualCall = builder.createCompiledNestedCall();
+          // assert
+          expect(actualCall.functionName).to.equal(expectedCall.functionName);
+        });
+        it('has no arguments or parameters', () => {
+          // arrange
+          const expectedCall = new FunctionCallStub()
+            .withArgumentCollection(new FunctionCallArgumentCollectionStub().withEmptyArguments());
+          const builder = new NestedFunctionArgumentCompilerBuilder()
+            .withNestedFunctionCall(expectedCall);
+          // act
+          const actualCall = builder.createCompiledNestedCall();
+          // assert
+          expect(actualCall.args.getAllParameterNames()).to.have.lengthOf(0);
+        });
+        it('does not compile expressions', () => {
+          // arrange
+          const expressionsCompilerStub = new ExpressionsCompilerStub();
+          const call = new FunctionCallStub()
+            .withArgumentCollection(new FunctionCallArgumentCollectionStub().withEmptyArguments());
+          const builder = new NestedFunctionArgumentCompilerBuilder()
+            .withNestedFunctionCall(call)
+            .withExpressionsCompiler(expressionsCompilerStub);
+          // act
+          builder.createCompiledNestedCall();
+          // assert
+          expect(expressionsCompilerStub.callHistory).to.have.lengthOf(0);
+        });
+      });
+      describe('with arguments', () => {
+        it('matches nested call name', () => {
+          // arrange
+          const expectedName = 'expected-nested-function-call-name';
+          const nestedCall = new FunctionCallStub()
+            .withFunctionName(expectedName)
+            .withArgumentCollection(new FunctionCallArgumentCollectionStub().withSomeArguments());
+          const builder = new NestedFunctionArgumentCompilerBuilder()
+            .withNestedFunctionCall(nestedCall);
+          // act
+          const call = builder.createCompiledNestedCall();
+          // assert
+          expect(call.functionName).to.equal(expectedName);
+        });
+        it('matches nested call parameters', () => {
+          // arrange
+          const expectedParameterNames = ['expectedFirstParameterName', 'expectedSecondParameterName'];
+          const nestedCall = new FunctionCallStub()
+            .withArgumentCollection(new FunctionCallArgumentCollectionStub()
+              .withArguments(expectedParameterNames.reduce((acc, name) => ({ ...acc, ...{ [name]: 'unimportant-value' } }), {})));
+          const builder = new NestedFunctionArgumentCompilerBuilder()
+            .withNestedFunctionCall(nestedCall);
+          // act
+          const call = builder.createCompiledNestedCall();
+          // assert
+          const actualParameterNames = call.args.getAllParameterNames();
+          expect(actualParameterNames.length).to.equal(expectedParameterNames.length);
+          expect(actualParameterNames).to.have.members(expectedParameterNames);
+        });
+        it('compiles args using parent parameters', () => {
+          // arrange
+          const expressionsCompilerStub = new ExpressionsCompilerStub();
+          const testParameterScenarios = [
+            {
+              parameterName: 'firstParameterName',
+              rawArgumentValue: 'first-raw-argument-value',
+              compiledArgumentValue: 'first-compiled-argument-value',
+            },
+            {
+              parameterName: 'secondParameterName',
+              rawArgumentValue: 'second-raw-argument-value',
+              compiledArgumentValue: 'second-compiled-argument-value',
+            },
+          ];
+          const parentCall = new FunctionCallStub().withArgumentCollection(
+            new FunctionCallArgumentCollectionStub().withSomeArguments(),
+          );
+          testParameterScenarios.forEach(({ rawArgumentValue }) => {
+            expressionsCompilerStub.setup({
+              givenCode: rawArgumentValue,
+              givenArgs: parentCall.args,
+              result: testParameterScenarios.find(
+                (r) => r.rawArgumentValue === rawArgumentValue,
+              )?.compiledArgumentValue ?? 'unexpected arguments',
+            });
+          });
+          const nestedCallArgs = new FunctionCallArgumentCollectionStub()
+            .withArguments(testParameterScenarios.reduce((
+              acc,
+              { parameterName, rawArgumentValue },
+            ) => ({ ...acc, ...{ [parameterName]: rawArgumentValue } }), {}));
+          const nestedCall = new FunctionCallStub()
+            .withArgumentCollection(nestedCallArgs);
+          const builder = new NestedFunctionArgumentCompilerBuilder()
+            .withExpressionsCompiler(expressionsCompilerStub)
+            .withParentFunctionCall(parentCall)
+            .withNestedFunctionCall(nestedCall);
+          // act
+          const compiledCall = builder.createCompiledNestedCall();
+          // assert
+          const expectedParameterNames = testParameterScenarios.map((p) => p.parameterName);
+          const actualParameterNames = compiledCall.args.getAllParameterNames();
+          expect(expectedParameterNames.length).to.equal(actualParameterNames.length);
+          expect(expectedParameterNames).to.have.members(actualParameterNames);
+          const getActualArgumentValue = (parameterName: string) => compiledCall
+            .args
+            .getArgument(parameterName)
+            .argumentValue;
+          testParameterScenarios.forEach(({ parameterName, compiledArgumentValue }) => {
+            expect(getActualArgumentValue(parameterName)).to.equal(compiledArgumentValue);
+          });
+        });
+        describe('when expression compiler returns empty', () => {
+          it('throws for required parameter', () => {
+            // arrange
+            const parameterName = 'requiredParameter';
+            const initialValue = 'initial-value';
+            const emptyCompiledExpression = '';
+            const expectedError = `Compilation resulted in empty value for required parameter: "${parameterName}"`;
+            const nestedCall = new FunctionCallStub()
+              .withArgumentCollection(new FunctionCallArgumentCollectionStub()
+                .withArgument(parameterName, initialValue));
+            const parentCall = new FunctionCallStub().withArgumentCollection(
+              new FunctionCallArgumentCollectionStub().withSomeArguments(),
+            );
+            const context = createContextWithParameter({
+              existingFunctionName: nestedCall.functionName,
+              existingParameterName: parameterName,
+              isExistingParameterOptional: false,
+            });
+            const expressionsCompilerStub = new ExpressionsCompilerStub()
+              .setup({
+                givenCode: initialValue,
+                givenArgs: parentCall.args,
+                result: emptyCompiledExpression,
+              });
+            const builder = new NestedFunctionArgumentCompilerBuilder()
+              .withExpressionsCompiler(expressionsCompilerStub)
+              .withParentFunctionCall(parentCall)
+              .withContext(context)
+              .withNestedFunctionCall(nestedCall);
+            // act
+            const act = () => builder.createCompiledNestedCall();
+            // assert
+            expect(act).to.throw(expectedError);
+          });
+          it('succeeds for optional parameter', () => {
+            // arrange
+            const parameterName = 'optionalParameter';
+            const initialValue = 'initial-value';
+            const emptyValue = '';
+            const nestedCall = new FunctionCallStub()
+              .withArgumentCollection(new FunctionCallArgumentCollectionStub()
+                .withArgument(parameterName, initialValue));
+            const parentCall = new FunctionCallStub().withArgumentCollection(
+              new FunctionCallArgumentCollectionStub().withSomeArguments(),
+            );
+            const context = createContextWithParameter({
+              existingFunctionName: nestedCall.functionName,
+              existingParameterName: parameterName,
+              isExistingParameterOptional: true,
+            });
+            const expressionsCompilerStub = new ExpressionsCompilerStub()
+              .setup({
+                givenCode: initialValue,
+                givenArgs: parentCall.args,
+                result: emptyValue,
+              });
+            const builder = new NestedFunctionArgumentCompilerBuilder()
+              .withExpressionsCompiler(expressionsCompilerStub)
+              .withParentFunctionCall(parentCall)
+              .withContext(context)
+              .withNestedFunctionCall(nestedCall);
+            // act
+            const compiledCall = builder.createCompiledNestedCall();
+            // assert
+            expect(compiledCall.args.hasArgument(parameterName)).toBeFalsy();
+          });
+        });
+      });
+    });
+  });
+});
+
+function createContextWithParameter(options: {
+  readonly existingFunctionName: string,
+  readonly existingParameterName: string,
+  readonly isExistingParameterOptional: boolean,
+}): FunctionCallCompilationContext {
+  const parameters = new FunctionParameterCollectionStub()
+    .withParameterName(options.existingParameterName, options.isExistingParameterOptional);
+  const func = createSharedFunctionStubWithCode()
+    .withName(options.existingFunctionName)
+    .withParameters(parameters);
+  const functions = new SharedFunctionCollectionStub()
+    .withFunctions(func);
+  const context = new FunctionCallCompilationContextStub()
+    .withAllFunctions(functions);
+  return context;
+}
+
+class NestedFunctionArgumentCompilerBuilder implements ArgumentCompiler {
+  private expressionsCompiler: IExpressionsCompiler = new ExpressionsCompilerStub();
+
+  private nestedFunctionCall: FunctionCall = new FunctionCallStub();
+
+  private parentFunctionCall: FunctionCall = new FunctionCallStub();
+
+  private context: FunctionCallCompilationContext = new FunctionCallCompilationContextStub();
+
+  private wrapError: ErrorWithContextWrapper = errorWithContextWrapperStub;
+
+  public withExpressionsCompiler(expressionsCompiler: IExpressionsCompiler): this {
+    this.expressionsCompiler = expressionsCompiler;
+    return this;
+  }
+
+  public withParentFunctionCall(parentFunctionCall: FunctionCall): this {
+    this.parentFunctionCall = parentFunctionCall;
+    return this;
+  }
+
+  public withNestedFunctionCall(nestedFunctionCall: FunctionCall): this {
+    this.nestedFunctionCall = nestedFunctionCall;
+    return this;
+  }
+
+  public withContext(context: FunctionCallCompilationContext): this {
+    this.context = context;
+    return this;
+  }
+
+  public withErrorWrapper(wrapError: ErrorWithContextWrapper): this {
+    this.wrapError = wrapError;
+    return this;
+  }
+
+  public createCompiledNestedCall(): FunctionCall {
+    const compiler = new NestedFunctionArgumentCompiler(
+      this.expressionsCompiler,
+      this.wrapError,
+    );
+    return compiler.createCompiledNestedCall(
+      this.nestedFunctionCall,
+      this.parentFunctionCall,
+      this.context,
+    );
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/InlineFunctionCallCompiler.spec.ts

@@ -0,0 +1,145 @@
+import { expect, describe, it } from 'vitest';
+import { InlineFunctionCallCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/SingleCall/Strategies/InlineFunctionCallCompiler';
+import { createSharedFunctionStubWithCode, createSharedFunctionStubWithCalls } from '@tests/unit/shared/Stubs/SharedFunctionStub';
+import { ExpressionsCompilerStub } from '@tests/unit/shared/Stubs/ExpressionsCompilerStub';
+import type { IExpressionsCompiler } from '@/application/Parser/Executable/Script/Compiler/Expressions/IExpressionsCompiler';
+import { FunctionCallStub } from '@tests/unit/shared/Stubs/FunctionCallStub';
+import { FunctionCallArgumentCollectionStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub';
+
+describe('InlineFunctionCallCompiler', () => {
+  describe('canCompile', () => {
+    it('returns `true` if function has code body', () => {
+      // arrange
+      const expected = true;
+      const func = createSharedFunctionStubWithCode();
+      const compiler = new InlineFunctionCallCompilerBuilder()
+        .build();
+      // act
+      const actual = compiler.canCompile(func);
+      // assert
+      expect(actual).to.equal(expected);
+    });
+    it('returns `false` if function does not have code body', () => {
+      // arrange
+      const expected = false;
+      const func = createSharedFunctionStubWithCalls();
+      const compiler = new InlineFunctionCallCompilerBuilder()
+        .build();
+      // act
+      const actual = compiler.canCompile(func);
+      // assert
+      expect(actual).to.equal(expected);
+    });
+  });
+  describe('compile', () => {
+    it('throws if function body is not code', () => {
+      // arrange
+      const expectedError = 'Unexpected function body type.';
+      const compiler = new InlineFunctionCallCompilerBuilder()
+        .build();
+      // act
+      const act = () => compiler.compileFunction(
+        createSharedFunctionStubWithCalls(),
+        new FunctionCallStub(),
+      );
+      // assert
+      expect(act).to.throw(expectedError);
+    });
+    it('compiles expressions with correct arguments', () => {
+      // arrange
+      const expressionsCompilerStub = new ExpressionsCompilerStub();
+      const expectedArgs = new FunctionCallArgumentCollectionStub();
+      const compiler = new InlineFunctionCallCompilerBuilder()
+        .withExpressionsCompiler(expressionsCompilerStub)
+        .build();
+      // act
+      compiler.compileFunction(
+        createSharedFunctionStubWithCode(),
+        new FunctionCallStub()
+          .withArgumentCollection(expectedArgs),
+      );
+      // assert
+      const actualArgs = expressionsCompilerStub.callHistory.map((call) => call.args[1]);
+      expect(actualArgs.every((arg) => arg === expectedArgs));
+    });
+    describe('execute', () => {
+      it('creates compiled code with compiled `execute`', () => {
+        // arrange
+        const func = createSharedFunctionStubWithCode();
+        const args = new FunctionCallArgumentCollectionStub();
+        const expectedCode = 'expected-code';
+        const expressionsCompilerStub = new ExpressionsCompilerStub()
+          .setup({
+            givenCode: func.body.code.execute,
+            givenArgs: args,
+            result: expectedCode,
+          });
+        const compiler = new InlineFunctionCallCompilerBuilder()
+          .withExpressionsCompiler(expressionsCompilerStub)
+          .build();
+        // act
+        const compiledCodes = compiler
+          .compileFunction(func, new FunctionCallStub().withArgumentCollection(args));
+        // assert
+        expect(compiledCodes).to.have.lengthOf(1);
+        const actualCode = compiledCodes[0].code;
+        expect(actualCode).to.equal(expectedCode);
+      });
+    });
+    describe('revert', () => {
+      it('compiles to `undefined` when given `undefined`', () => {
+        // arrange
+        const expected = undefined;
+        const revertCode = undefined;
+        const func = createSharedFunctionStubWithCode()
+          .withRevertCode(revertCode);
+        const compiler = new InlineFunctionCallCompilerBuilder()
+          .build();
+        // act
+        const compiledCodes = compiler
+          .compileFunction(func, new FunctionCallStub());
+        // assert
+        expect(compiledCodes).to.have.lengthOf(1);
+        const actualRevertCode = compiledCodes[0].revertCode;
+        expect(actualRevertCode).to.equal(expected);
+      });
+      it('creates compiled revert code with compiled `revert`', () => {
+        // arrange
+        const revertCode = 'revert-code-input';
+        const func = createSharedFunctionStubWithCode()
+          .withRevertCode(revertCode);
+        const args = new FunctionCallArgumentCollectionStub();
+        const expectedRevertCode = 'expected-revert-code';
+        const expressionsCompilerStub = new ExpressionsCompilerStub()
+          .setup({
+            givenCode: revertCode,
+            givenArgs: args,
+            result: expectedRevertCode,
+          });
+        const compiler = new InlineFunctionCallCompilerBuilder()
+          .withExpressionsCompiler(expressionsCompilerStub)
+          .build();
+        // act
+        const compiledCodes = compiler
+          .compileFunction(func, new FunctionCallStub().withArgumentCollection(args));
+        // assert
+        expect(compiledCodes).to.have.lengthOf(1);
+        const actualRevertCode = compiledCodes[0].revertCode;
+        expect(actualRevertCode).to.equal(expectedRevertCode);
+      });
+    });
+  });
+});
+
+class InlineFunctionCallCompilerBuilder {
+  private expressionsCompiler: IExpressionsCompiler = new ExpressionsCompilerStub();
+
+  public build(): InlineFunctionCallCompiler {
+    return new InlineFunctionCallCompiler(this.expressionsCompiler);
+  }
+
+  public withExpressionsCompiler(expressionsCompiler: IExpressionsCompiler): this {
+    this.expressionsCompiler = expressionsCompiler;
+    return this;
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCallParser.spec.ts

@@ -0,0 +1,84 @@
+import { describe, it, expect } from 'vitest';
+import { parseFunctionCalls } from '@/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCallParser';
+import { FunctionCallDataStub } from '@tests/unit/shared/Stubs/FunctionCallDataStub';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('FunctionCallParser', () => {
+  describe('parseFunctionCalls', () => {
+    it('throws if call is not an object', () => {
+      // arrange
+      const expectedError = 'called function(s) must be an object';
+      const invalidCalls = ['string', 33, false];
+      invalidCalls.forEach((invalidCall) => {
+        // act
+        const act = () => parseFunctionCalls(invalidCall as never);
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+    });
+    describe('throws if call sequence has undefined function name', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const expectedError = 'missing function name in function call';
+        const data = [
+          new FunctionCallDataStub().withName('function-name'),
+          new FunctionCallDataStub().withName(absentValue),
+        ];
+        // act
+        const act = () => parseFunctionCalls(data);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+    it('parses single call as expected', () => {
+      // arrange
+      const expectedFunctionName = 'functionName';
+      const expectedParameterName = 'parameterName';
+      const expectedArgumentValue = 'argumentValue';
+      const data = new FunctionCallDataStub()
+        .withName(expectedFunctionName)
+        .withParameters({ [expectedParameterName]: expectedArgumentValue });
+      // act
+      const actual = parseFunctionCalls(data);
+      // assert
+      expect(actual).to.have.lengthOf(1);
+      const call = actual[0];
+      expect(call.functionName).to.equal(expectedFunctionName);
+      const { args } = call;
+      expect(args.getAllParameterNames()).to.have.lengthOf(1);
+      expect(args.hasArgument(expectedParameterName)).to.equal(
+        true,
+        `Does not include expected parameter: "${expectedParameterName}"\n`
+          + `But includes: "${args.getAllParameterNames()}"`,
+      );
+      const argument = args.getArgument(expectedParameterName);
+      expect(argument.parameterName).to.equal(expectedParameterName);
+      expect(argument.argumentValue).to.equal(expectedArgumentValue);
+    });
+    it('parses multiple calls as expected', () => {
+      // arrange
+      const getFunctionName = (index: number) => `functionName${index}`;
+      const getParameterName = (index: number) => `parameterName${index}`;
+      const getArgumentValue = (index: number) => `argumentValue${index}`;
+      const createCall = (index: number) => new FunctionCallDataStub()
+        .withName(getFunctionName(index))
+        .withParameters({ [getParameterName(index)]: getArgumentValue(index) });
+      const calls = [createCall(0), createCall(1), createCall(2), createCall(3)];
+      // act
+      const actual = parseFunctionCalls(calls);
+      // assert
+      expect(actual).to.have.lengthOf(calls.length);
+      for (let i = 0; i < calls.length; i++) {
+        const call = actual[i];
+        const expectedParameterName = getParameterName(i);
+        const expectedArgumentValue = getArgumentValue(i);
+        expect(call.functionName).to.equal(getFunctionName(i));
+        expect(call.args.getAllParameterNames()).to.have.lengthOf(1);
+        expect(call.args.hasArgument(expectedParameterName)).to.equal(true);
+        const argument = call.args.getArgument(expectedParameterName);
+        expect(argument.parameterName).to.equal(expectedParameterName);
+        expect(argument.argumentValue).to.equal(expectedArgumentValue);
+      }
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Function/Call/ParsedFunctionCall.spec.ts

@@ -0,0 +1,68 @@
+import { describe, it, expect } from 'vitest';
+import { ParsedFunctionCall } from '@/application/Parser/Executable/Script/Compiler/Function/Call/ParsedFunctionCall';
+import type { IReadOnlyFunctionCallArgumentCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Argument/IFunctionCallArgumentCollection';
+import { FunctionCallArgumentCollectionStub } from '@tests/unit/shared/Stubs/FunctionCallArgumentCollectionStub';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('ParsedFunctionCall', () => {
+  describe('ctor', () => {
+    describe('args', () => {
+      it('sets args as expected', () => {
+        // arrange
+        const expected = new FunctionCallArgumentCollectionStub()
+          .withArgument('testParameter', 'testValue');
+        // act
+        const sut = new FunctionCallBuilder()
+          .withArgs(expected)
+          .build();
+        // assert
+        expect(sut.args).to.deep.equal(expected);
+      });
+    });
+    describe('functionName', () => {
+      describe('throws when function name is missing', () => {
+        itEachAbsentStringValue((absentValue) => {
+          // arrange
+          const expectedError = 'missing function name in function call';
+          const functionName = absentValue;
+          // act
+          const act = () => new FunctionCallBuilder()
+            .withFunctionName(functionName)
+            .build();
+          // assert
+          expect(act).to.throw(expectedError);
+        }, { excludeNull: true, excludeUndefined: true });
+      });
+      it('sets function name as expected', () => {
+        // arrange
+        const expected = 'expectedFunctionName';
+        // act
+        const sut = new FunctionCallBuilder()
+          .withFunctionName(expected)
+          .build();
+        // assert
+        expect(sut.functionName).to.equal(expected);
+      });
+    });
+  });
+});
+
+class FunctionCallBuilder {
+  private functionName = 'functionName';
+
+  private args: IReadOnlyFunctionCallArgumentCollection = new FunctionCallArgumentCollectionStub();
+
+  public withFunctionName(functionName: string) {
+    this.functionName = functionName;
+    return this;
+  }
+
+  public withArgs(args: IReadOnlyFunctionCallArgumentCollection) {
+    this.args = args;
+    return this;
+  }
+
+  public build() {
+    return new ParsedFunctionCall(this.functionName, this.args);
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/ExpectFunctionBodyType.ts

@@ -0,0 +1,26 @@
+import type {
+  CallFunctionBody, CodeFunctionBody, SharedFunctionBody,
+} from '@/application/Parser/Executable/Script/Compiler/Function/ISharedFunction';
+import { FunctionBodyType } from '@/application/Parser/Executable/Script/Compiler/Function/ISharedFunction';
+import { formatAssertionMessage } from '@tests/shared/FormatAssertionMessage';
+
+export function expectCodeFunctionBody(
+  body: SharedFunctionBody,
+): asserts body is CodeFunctionBody {
+  expectBodyType(body, FunctionBodyType.Code);
+}
+
+export function expectCallsFunctionBody(
+  body: SharedFunctionBody,
+): asserts body is CallFunctionBody {
+  expectBodyType(body, FunctionBodyType.Calls);
+}
+
+function expectBodyType(body: SharedFunctionBody, expectedType: FunctionBodyType) {
+  const actualType = body.type;
+  expect(actualType).to.equal(expectedType, formatAssertionMessage([
+    `Actual: ${FunctionBodyType[actualType]}`,
+    `Expected: ${FunctionBodyType[expectedType]}`,
+    `Body: ${JSON.stringify(body)}`,
+  ]));
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameter.spec.ts

@@ -0,0 +1,50 @@
+import { describe, it, expect } from 'vitest';
+import { FunctionParameter } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameter';
+import { testParameterName } from '../../ParameterNameTestRunner';
+
+describe('FunctionParameter', () => {
+  describe('name', () => {
+    testParameterName(
+      (parameterName) => new FunctionParameterBuilder()
+        .withName(parameterName)
+        .build()
+        .name,
+    );
+  });
+  describe('isOptional', () => {
+    describe('sets as expected', () => {
+      // arrange
+      const expectedValues = [true, false];
+      for (const expected of expectedValues) {
+        it(expected.toString(), () => {
+          // act
+          const sut = new FunctionParameterBuilder()
+            .withIsOptional(expected)
+            .build();
+          // expect
+          expect(sut.isOptional).to.equal(expected);
+        });
+      }
+    });
+  });
+});
+
+class FunctionParameterBuilder {
+  private name = 'parameterFromParameterBuilder';
+
+  private isOptional = false;
+
+  public withName(name: string) {
+    this.name = name;
+    return this;
+  }
+
+  public withIsOptional(isOptional: boolean) {
+    this.isOptional = isOptional;
+    return this;
+  }
+
+  public build() {
+    return new FunctionParameter(this.name, this.isOptional);
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameterCollection.spec.ts

@@ -0,0 +1,35 @@
+import { describe, it, expect } from 'vitest';
+import { FunctionParameterCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameterCollection';
+import { FunctionParameterStub } from '@tests/unit/shared/Stubs/FunctionParameterStub';
+
+describe('FunctionParameterCollection', () => {
+  it('all returns added parameters as expected', () => {
+    // arrange
+    const expected = [
+      new FunctionParameterStub().withName('1'),
+      new FunctionParameterStub().withName('2').withOptional(true),
+      new FunctionParameterStub().withName('3').withOptional(false),
+    ];
+    const sut = new FunctionParameterCollection();
+    for (const parameter of expected) {
+      sut.addParameter(parameter);
+    }
+    // act
+    const actual = sut.all;
+    // assert
+    expect(expected).to.deep.equal(actual);
+  });
+  it('throws when function parameters have same names', () => {
+    // arrange
+    const parameterName = 'duplicate-parameter';
+    const expectedError = `duplicate parameter name: "${parameterName}"`;
+    const sut = new FunctionParameterCollection();
+    sut.addParameter(new FunctionParameterStub().withName(parameterName));
+    // act
+    const act = () => sut.addParameter(
+      new FunctionParameterStub().withName(parameterName),
+    );
+    // assert
+    expect(act).to.throw(expectedError);
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameterCollectionFactory.spec.ts

@@ -0,0 +1,23 @@
+import { describe, it, expect } from 'vitest';
+import { FunctionParameterCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameterCollection';
+import { createFunctionParameterCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameterCollectionFactory';
+import { itIsTransientFactory } from '@tests/unit/shared/TestCases/TransientFactoryTests';
+
+describe('FunctionParameterCollectionFactory', () => {
+  describe('createFunctionParameterCollection', () => {
+    describe('it is a transient factory', () => {
+      itIsTransientFactory({
+        getter: () => createFunctionParameterCollection(),
+        expectedType: FunctionParameterCollection,
+      });
+    });
+    it('returns an empty collection', () => {
+      // arrange
+      const expectedInitialParametersCount = 0;
+      // act
+      const collection = createFunctionParameterCollection();
+      // assert
+      expect(collection.all).to.have.lengthOf(expectedInitialParametersCount);
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Function/SharedFunction.spec.ts

@@ -0,0 +1,240 @@
+import { describe, it, expect } from 'vitest';
+import type { IReadOnlyFunctionParameterCollection } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/IFunctionParameterCollection';
+import { FunctionParameterCollectionStub } from '@tests/unit/shared/Stubs/FunctionParameterCollectionStub';
+import { createCallerFunction, createFunctionWithInlineCode } from '@/application/Parser/Executable/Script/Compiler/Function/SharedFunction';
+import type { FunctionCall } from '@/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCall';
+import { FunctionCallStub } from '@tests/unit/shared/Stubs/FunctionCallStub';
+import { type CallFunctionBody, FunctionBodyType, type ISharedFunction } from '@/application/Parser/Executable/Script/Compiler/Function/ISharedFunction';
+import {
+  getAbsentStringTestCases, itEachAbsentCollectionValue,
+  itEachAbsentStringValue,
+} from '@tests/unit/shared/TestCases/AbsentTests';
+import { expectCallsFunctionBody, expectCodeFunctionBody } from './ExpectFunctionBodyType';
+
+describe('SharedFunction', () => {
+  describe('SharedFunction', () => {
+    describe('name', () => {
+      runForEachFactoryMethod((build) => {
+        it('sets as expected', () => {
+          // arrange
+          const expected = 'expected-function-name';
+          const builder = new SharedFunctionBuilder()
+            .withName(expected);
+          // act
+          const sut = build(builder);
+          // assert
+          expect(sut.name).equal(expected);
+        });
+        describe('throws when absent', () => {
+          itEachAbsentStringValue((absentValue) => {
+            // arrange
+            const expectedError = 'missing function name';
+            const builder = new SharedFunctionBuilder()
+              .withName(absentValue);
+            // act
+            const act = () => build(builder);
+            // assert
+            expect(act).to.throw(expectedError);
+          }, { excludeNull: true, excludeUndefined: true });
+        });
+      });
+    });
+    describe('parameters', () => {
+      runForEachFactoryMethod((build) => {
+        it('sets as expected', () => {
+          // arrange
+          const expected = new FunctionParameterCollectionStub()
+            .withParameterName('test-parameter');
+          const builder = new SharedFunctionBuilder()
+            .withParameters(expected);
+          // act
+          const sut = build(builder);
+          // assert
+          expect(sut.parameters).equal(expected);
+        });
+      });
+    });
+  });
+  describe('createFunctionWithInlineCode', () => {
+    describe('code', () => {
+      it('sets as expected', () => {
+        // arrange
+        const expected = 'expected-code';
+        // act
+        const sut = new SharedFunctionBuilder()
+          .withCode(expected)
+          .createFunctionWithInlineCode();
+        // assert
+        expectCodeFunctionBody(sut.body);
+        expect(sut.body.code.execute).equal(expected);
+      });
+      describe('throws if absent', () => {
+        itEachAbsentStringValue((absentValue) => {
+          // arrange
+          const functionName = 'expected-function-name';
+          const expectedError = `undefined code in function "${functionName}"`;
+          const invalidValue = absentValue;
+          // act
+          const act = () => new SharedFunctionBuilder()
+            .withName(functionName)
+            .withCode(invalidValue)
+            .createFunctionWithInlineCode();
+          // assert
+          expect(act).to.throw(expectedError);
+        }, { excludeUndefined: true, excludeNull: true });
+      });
+    });
+    describe('revertCode', () => {
+      it('sets as expected', () => {
+        // arrange
+        const revertCodeTestValues: readonly (string | undefined)[] = [
+          'expected-revert-code',
+          ...getAbsentStringTestCases({
+            excludeNull: true,
+          }).map((testCase) => testCase.absentValue),
+        ];
+        for (const revertCode of revertCodeTestValues) {
+          // act
+          const sut = new SharedFunctionBuilder()
+            .withRevertCode(revertCode)
+            .createFunctionWithInlineCode();
+          // assert
+          expectCodeFunctionBody(sut.body);
+          expect(sut.body.code.revert).equal(revertCode);
+        }
+      });
+    });
+    it('sets type as expected', () => {
+      // arrange
+      const expectedType = FunctionBodyType.Code;
+      // act
+      const sut = new SharedFunctionBuilder()
+        .createFunctionWithInlineCode();
+      // assert
+      expect(sut.body.type).equal(expectedType);
+    });
+    it('calls are undefined', () => {
+      // arrange
+      const expectedCalls = undefined;
+      // act
+      const sut = new SharedFunctionBuilder()
+        .createFunctionWithInlineCode();
+      // assert
+      expect((sut.body as CallFunctionBody).calls).equal(expectedCalls);
+    });
+  });
+  describe('createCallerFunction', () => {
+    describe('rootCallSequence', () => {
+      it('sets as expected', () => {
+        // arrange
+        const expected = [
+          new FunctionCallStub().withFunctionName('firstFunction'),
+          new FunctionCallStub().withFunctionName('secondFunction'),
+        ];
+        // act
+        const sut = new SharedFunctionBuilder()
+          .withRootCallSequence(expected)
+          .createCallerFunction();
+        // assert
+        expectCallsFunctionBody(sut.body);
+        expect(sut.body.calls).equal(expected);
+      });
+      describe('throws if missing', () => {
+        itEachAbsentCollectionValue<FunctionCall>((absentValue) => {
+          // arrange
+          const functionName = 'invalidFunction';
+          const rootCallSequence = absentValue;
+          const expectedError = `missing call sequence in function "${functionName}"`;
+          // act
+          const act = () => new SharedFunctionBuilder()
+            .withName(functionName)
+            .withRootCallSequence(rootCallSequence)
+            .createCallerFunction();
+          // assert
+          expect(act).to.throw(expectedError);
+        }, { excludeUndefined: true, excludeNull: true });
+      });
+    });
+    it('sets type as expected', () => {
+      // arrange
+      const expectedType = FunctionBodyType.Calls;
+      // act
+      const sut = new SharedFunctionBuilder()
+        .createCallerFunction();
+      // assert
+      expect(sut.body.type).equal(expectedType);
+    });
+  });
+});
+
+function runForEachFactoryMethod(
+  act: (action: (sut: SharedFunctionBuilder) => ISharedFunction) => void,
+): void {
+  describe('createCallerFunction', () => {
+    const action = (builder: SharedFunctionBuilder) => builder.createCallerFunction();
+    act(action);
+  });
+  describe('createFunctionWithInlineCode', () => {
+    const action = (builder: SharedFunctionBuilder) => builder.createFunctionWithInlineCode();
+    act(action);
+  });
+}
+
+/*
+  Using an abstraction here allows for easy refactorings in
+  parameters or moving between functional and object-oriented
+  solutions without refactorings all tests.
+*/
+class SharedFunctionBuilder {
+  private name = 'name';
+
+  private parameters: IReadOnlyFunctionParameterCollection = new FunctionParameterCollectionStub();
+
+  private callSequence: readonly FunctionCall[] = [new FunctionCallStub()];
+
+  private code = `[${SharedFunctionBuilder.name}] code`;
+
+  private revertCode: string | undefined = `[${SharedFunctionBuilder.name}] revert-code`;
+
+  public createCallerFunction(): ISharedFunction {
+    return createCallerFunction(
+      this.name,
+      this.parameters,
+      this.callSequence,
+    );
+  }
+
+  public createFunctionWithInlineCode(): ISharedFunction {
+    return createFunctionWithInlineCode(
+      this.name,
+      this.parameters,
+      this.code,
+      this.revertCode,
+    );
+  }
+
+  public withName(name: string) {
+    this.name = name;
+    return this;
+  }
+
+  public withParameters(parameters: IReadOnlyFunctionParameterCollection) {
+    this.parameters = parameters;
+    return this;
+  }
+
+  public withCode(code: string) {
+    this.code = code;
+    return this;
+  }
+
+  public withRevertCode(revertCode: string | undefined) {
+    this.revertCode = revertCode;
+    return this;
+  }
+
+  public withRootCallSequence(callSequence: readonly FunctionCall[]) {
+    this.callSequence = callSequence;
+    return this;
+  }
+}

tests/unit/application/Parser/Executable/Script/Compiler/Function/SharedFunctionCollection.spec.ts

@@ -0,0 +1,77 @@
+import { describe, it, expect } from 'vitest';
+import { SharedFunctionCollection } from '@/application/Parser/Executable/Script/Compiler/Function/SharedFunctionCollection';
+import { createSharedFunctionStubWithCode, createSharedFunctionStubWithCalls } from '@tests/unit/shared/Stubs/SharedFunctionStub';
+import { FunctionCallStub } from '@tests/unit/shared/Stubs/FunctionCallStub';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('SharedFunctionCollection', () => {
+  describe('addFunction', () => {
+    it('throws if function with same name already exists', () => {
+      // arrange
+      const functionName = 'duplicate-function';
+      const expectedError = `function with name ${functionName} already exists`;
+      const func = createSharedFunctionStubWithCode()
+        .withName('duplicate-function');
+      const sut = new SharedFunctionCollection();
+      sut.addFunction(func);
+      // act
+      const act = () => sut.addFunction(func);
+      // assert
+      expect(act).to.throw(expectedError);
+    });
+  });
+  describe('getFunctionByName', () => {
+    describe('throws if name is absent', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const expectedError = 'missing function name';
+        const sut = new SharedFunctionCollection();
+        // act
+        const act = () => sut.getFunctionByName(absentValue);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+    it('throws if function does not exist', () => {
+      // arrange
+      const name = 'unique-name';
+      const expectedError = `Called function is not defined: "${name}"`;
+      const func = createSharedFunctionStubWithCode()
+        .withName('unexpected-name');
+      const sut = new SharedFunctionCollection();
+      sut.addFunction(func);
+      // act
+      const act = () => sut.getFunctionByName(name);
+      // assert
+      expect(act).to.throw(expectedError);
+    });
+    describe('returns existing function', () => {
+      it('when function with inline code is added', () => {
+        // arrange
+        const expected = createSharedFunctionStubWithCode()
+          .withName('expected-function-name');
+        const sut = new SharedFunctionCollection();
+        // act
+        sut.addFunction(expected);
+        const actual = sut.getFunctionByName(expected.name);
+        // assert
+        expect(actual).to.equal(expected);
+      });
+      it('when calling function is added', () => {
+        // arrange
+        const callee = createSharedFunctionStubWithCode()
+          .withName('calleeFunction');
+        const caller = createSharedFunctionStubWithCalls()
+          .withName('callerFunction')
+          .withCalls(new FunctionCallStub().withFunctionName(callee.name));
+        const sut = new SharedFunctionCollection();
+        // act
+        sut.addFunction(callee);
+        sut.addFunction(caller);
+        const actual = sut.getFunctionByName(caller.name);
+        // assert
+        expect(actual).to.equal(caller);
+      });
+    });
+  });
+});

tests/unit/application/Parser/Executable/Script/Compiler/Function/SharedFunctionsParser.spec.ts

@@ -0,0 +1,403 @@
+import { describe, it, expect } from 'vitest';
+import type { FunctionData, CodeInstruction } from '@/application/collections/';
+import type { ISharedFunction } from '@/application/Parser/Executable/Script/Compiler/Function/ISharedFunction';
+import { SharedFunctionsParser, type FunctionParameterFactory } from '@/application/Parser/Executable/Script/Compiler/Function/SharedFunctionsParser';
+import { createFunctionDataWithCode, createFunctionDataWithoutCallOrCode } from '@tests/unit/shared/Stubs/FunctionDataStub';
+import { ParameterDefinitionDataStub } from '@tests/unit/shared/Stubs/ParameterDefinitionDataStub';
+import { FunctionCallDataStub } from '@tests/unit/shared/Stubs/FunctionCallDataStub';
+import { itEachAbsentCollectionValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import type { ILanguageSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/ILanguageSyntax';
+import { LanguageSyntaxStub } from '@tests/unit/shared/Stubs/LanguageSyntaxStub';
+import { itIsSingletonFactory } from '@tests/unit/shared/TestCases/SingletonFactoryTests';
+import { CodeValidatorStub } from '@tests/unit/shared/Stubs/CodeValidatorStub';
+import type { ICodeValidator } from '@/application/Parser/Executable/Script/Validation/ICodeValidator';
+import { NoEmptyLines } from '@/application/Parser/Executable/Script/Validation/Rules/NoEmptyLines';
+import { NoDuplicatedLines } from '@/application/Parser/Executable/Script/Validation/Rules/NoDuplicatedLines';
+import type { ErrorWithContextWrapper } from '@/application/Parser/ContextualError';
+import { FunctionParameterStub } from '@tests/unit/shared/Stubs/FunctionParameterStub';
+import { errorWithContextWrapperStub } from '@tests/unit/shared/Stubs/ErrorWithContextWrapperStub';
+import { itThrowsContextualError } from '@tests/unit/application/Parser/ContextualErrorTester';
+import type { FunctionParameterCollectionFactory } from '@/application/Parser/Executable/Script/Compiler/Function/Parameter/FunctionParameterCollectionFactory';
+import { FunctionParameterCollectionStub } from '@tests/unit/shared/Stubs/FunctionParameterCollectionStub';
+import { expectCallsFunctionBody, expectCodeFunctionBody } from './ExpectFunctionBodyType';
+
+describe('SharedFunctionsParser', () => {
+  describe('instance', () => {
+    itIsSingletonFactory({
+      getter: () => SharedFunctionsParser.instance,
+      expectedType: SharedFunctionsParser,
+    });
+  });
+  describe('parseFunctions', () => {
+    describe('validates functions', () => {
+      it('throws when functions have no names', () => {
+        // arrange
+        const invalidFunctions = [
+          createFunctionDataWithCode()
+            .withCode('test function 1')
+            .withName(' '), // Whitespace,
+          createFunctionDataWithCode()
+            .withCode('test function 2')
+            .withName(undefined as unknown as string), // Undefined
+          createFunctionDataWithCode()
+            .withCode('test function 3')
+            .withName(''), // Empty
+        ];
+        const expectedError = `Some function(s) have no names:\n${invalidFunctions.map((f) => JSON.stringify(f)).join('\n')}`;
+        // act
+        const act = () => new ParseFunctionsCallerWithDefaults()
+          .withFunctions(invalidFunctions)
+          .parseFunctions();
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+      it('throws when functions have same names', () => {
+        // arrange
+        const name = 'same-func-name';
+        const expectedError = `duplicate function name: "${name}"`;
+        const functions = [
+          createFunctionDataWithCode().withName(name),
+          createFunctionDataWithCode().withName(name),
+        ];
+        // act
+        const act = () => new ParseFunctionsCallerWithDefaults()
+          .withFunctions(functions)
+          .parseFunctions();
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+      describe('throws when when function have duplicate code', () => {
+        it('code', () => {
+          // arrange
+          const code = 'duplicate-code';
+          const expectedError = `duplicate "code" in functions: "${code}"`;
+          const functions = [
+            createFunctionDataWithoutCallOrCode().withName('func-1').withCode(code),
+            createFunctionDataWithoutCallOrCode().withName('func-2').withCode(code),
+          ];
+          // act
+          const act = () => new ParseFunctionsCallerWithDefaults()
+            .withFunctions(functions)
+            .parseFunctions();
+          // assert
+          expect(act).to.throw(expectedError);
+        });
+        it('revertCode', () => {
+          // arrange
+          const revertCode = 'duplicate-revert-code';
+          const expectedError = `duplicate "revertCode" in functions: "${revertCode}"`;
+          const functions = [
+            createFunctionDataWithoutCallOrCode()
+              .withName('func-1').withCode('code-1').withRevertCode(revertCode),
+            createFunctionDataWithoutCallOrCode()
+              .withName('func-2').withCode('code-2').withRevertCode(revertCode),
+          ];
+          // act
+          const act = () => new ParseFunctionsCallerWithDefaults()
+            .withFunctions(functions)
+            .parseFunctions();
+          // assert
+          expect(act).to.throw(expectedError);
+        });
+      });
+      describe('ensures either call or code is defined', () => {
+        it('both code and call are defined', () => {
+          // arrange
+          const functionName = 'invalid-function';
+          const expectedError = `both "code" and "call" are defined in "${functionName}"`;
+          const invalidFunction = createFunctionDataWithoutCallOrCode()
+            .withName(functionName)
+            .withCode('code')
+            .withMockCall();
+          // act
+          const act = () => new ParseFunctionsCallerWithDefaults()
+            .withFunctions([invalidFunction])
+            .parseFunctions();
+          // assert
+          expect(act).to.throw(expectedError);
+        });
+        it('neither code and call is defined', () => {
+          // arrange
+          const functionName = 'invalid-function';
+          const expectedError = `neither "code" or "call" is defined in "${functionName}"`;
+          const invalidFunction = createFunctionDataWithoutCallOrCode()
+            .withName(functionName);
+          // act
+          const act = () => new ParseFunctionsCallerWithDefaults()
+            .withFunctions([invalidFunction])
+            .parseFunctions();
+          // assert
+          expect(act).to.throw(expectedError);
+        });
+      });
+      describe('throws when parameters type is not as expected', () => {
+        const testScenarios = [
+          {
+            state: 'when not an array',
+            invalidType: 5,
+          },
+          {
+            state: 'when array but not of objects',
+            invalidType: ['a', { a: 'b' }],
+          },
+        ];
+        for (const testCase of testScenarios) {
+          it(testCase.state, () => {
+            // arrange
+            const func = createFunctionDataWithCode()
+              .withParametersObject(testCase.invalidType as never);
+            const expectedError = `parameters must be an array of objects in function(s) "${func.name}"`;
+            // act
+            const act = () => new ParseFunctionsCallerWithDefaults()
+              .withFunctions([func])
+              .parseFunctions();
+            // assert
+            expect(act).to.throw(expectedError);
+          });
+        }
+      });
+      it('validates function code as expected when code is defined', () => {
+        // arrange
+        const expectedRules = [NoEmptyLines, NoDuplicatedLines];
+        const functionData = createFunctionDataWithCode()
+          .withCode('expected code to be validated')
+          .withRevertCode('expected revert code to be validated');
+        const validator = new CodeValidatorStub();
+        // act
+        new ParseFunctionsCallerWithDefaults()
+          .withFunctions([functionData])
+          .withValidator(validator)
+          .parseFunctions();
+        // assert
+        validator.assertHistory({
+          validatedCodes: [functionData.code, functionData.revertCode],
+          rules: expectedRules,
+        });
+      });
+      describe('parameter creation', () => {
+        describe('rethrows including function name when creating parameter throws', () => {
+          // arrange
+          const invalidParameterName = 'invalid-function-parameter-name';
+          const functionName = 'functionName';
+          const expectedErrorMessage = `Failed to create parameter: ${invalidParameterName} for function "${functionName}"`;
+          const expectedInnerError = new Error('injected error');
+          const parameterFactory: FunctionParameterFactory = () => {
+            throw expectedInnerError;
+          };
+          const functionData = createFunctionDataWithCode()
+            .withName(functionName)
+            .withParameters(new ParameterDefinitionDataStub().withName(invalidParameterName));
+          itThrowsContextualError({
+            // act
+            throwingAction: (wrapError) => {
+              new ParseFunctionsCallerWithDefaults()
+                .withFunctions([functionData])
+                .withFunctionParameterFactory(parameterFactory)
+                .withErrorWrapper(wrapError)
+                .parseFunctions();
+            },
+            // assert
+            expectedWrappedError: expectedInnerError,
+            expectedContextMessage: expectedErrorMessage,
+          });
+        });
+      });
+    });
+    describe('given empty functions, returns empty collection', () => {
+      itEachAbsentCollectionValue<FunctionData>((absentValue) => {
+        // act
+        const actual = new ParseFunctionsCallerWithDefaults()
+          .withFunctions(absentValue)
+          .parseFunctions();
+        // assert
+        expect(actual).to.not.equal(undefined);
+      }, { excludeUndefined: true, excludeNull: true });
+    });
+    describe('function with inline code', () => {
+      it('parses single function with code as expected', () => {
+        // arrange
+        const name = 'function-name';
+        const expected = createFunctionDataWithoutCallOrCode()
+          .withName(name)
+          .withCode('expected-code')
+          .withRevertCode('expected-revert-code')
+          .withParameters(
+            new ParameterDefinitionDataStub().withName('expectedParameter').withOptionality(true),
+            new ParameterDefinitionDataStub().withName('expectedParameter2').withOptionality(false),
+          );
+        // act
+        const collection = new ParseFunctionsCallerWithDefaults()
+          .withFunctions([expected])
+          .parseFunctions();
+        // expect
+        const actual = collection.getFunctionByName(name);
+        expectEqualName(expected, actual);
+        expectEqualParameters(expected, actual);
+        expectEqualFunctionWithInlineCode(expected, actual);
+      });
+    });
+    describe('function with calls', () => {
+      it('parses single function with call as expected', () => {
+        // arrange
+        const call = new FunctionCallDataStub()
+          .withName('calleeFunction')
+          .withParameters({ test: 'value' });
+        const data = createFunctionDataWithoutCallOrCode()
+          .withName('caller-function')
+          .withCall(call);
+        // act
+        const collection = new ParseFunctionsCallerWithDefaults()
+          .withFunctions([data])
+          .parseFunctions();
+        // expect
+        const actual = collection.getFunctionByName(data.name);
+        expectEqualName(data, actual);
+        expectEqualParameters(data, actual);
+        expectEqualCalls([call], actual);
+      });
+      it('parses multiple functions with call as expected', () => {
+        // arrange
+        const call1 = new FunctionCallDataStub()
+          .withName('calleeFunction1')
+          .withParameters({ param: 'value' });
+        const call2 = new FunctionCallDataStub()
+          .withName('calleeFunction2')
+          .withParameters({ param2: 'value2' });
+        const caller1 = createFunctionDataWithoutCallOrCode()
+          .withName('caller-function')
+          .withCall(call1);
+        const caller2 = createFunctionDataWithoutCallOrCode()
+          .withName('caller-function-2')
+          .withCall([call1, call2]);
+        // act
+        const collection = new ParseFunctionsCallerWithDefaults()
+          .withFunctions([caller1, caller2])
+          .parseFunctions();
+        // expect
+        const compiledCaller1 = collection.getFunctionByName(caller1.name);
+        expectEqualName(caller1, compiledCaller1);
+        expectEqualParameters(caller1, compiledCaller1);
+        expectEqualCalls([call1], compiledCaller1);
+        const compiledCaller2 = collection.getFunctionByName(caller2.name);
+        expectEqualName(caller2, compiledCaller2);
+        expectEqualParameters(caller2, compiledCaller2);
+        expectEqualCalls([call1, call2], compiledCaller2);
+      });
+    });
+  });
+});
+
+class ParseFunctionsCallerWithDefaults {
+  private syntax: ILanguageSyntax = new LanguageSyntaxStub();
+
+  private codeValidator: ICodeValidator = new CodeValidatorStub();
+
+  private functions: readonly FunctionData[] = [createFunctionDataWithCode()];
+
+  private wrapError: ErrorWithContextWrapper = errorWithContextWrapperStub;
+
+  private parameterFactory: FunctionParameterFactory = (
+    name: string,
+    isOptional: boolean,
+  ) => new FunctionParameterStub()
+    .withName(name)
+    .withOptional(isOptional);
+
+  private parameterCollectionFactory
+  : FunctionParameterCollectionFactory = () => new FunctionParameterCollectionStub();
+
+  public withSyntax(syntax: ILanguageSyntax) {
+    this.syntax = syntax;
+    return this;
+  }
+
+  public withValidator(codeValidator: ICodeValidator) {
+    this.codeValidator = codeValidator;
+    return this;
+  }
+
+  public withFunctions(functions: readonly FunctionData[]) {
+    this.functions = functions;
+    return this;
+  }
+
+  public withErrorWrapper(wrapError: ErrorWithContextWrapper): this {
+    this.wrapError = wrapError;
+    return this;
+  }
+
+  public withFunctionParameterFactory(parameterFactory: FunctionParameterFactory): this {
+    this.parameterFactory = parameterFactory;
+    return this;
+  }
+
+  public withParameterCollectionFactory(
+    parameterCollectionFactory: FunctionParameterCollectionFactory,
+  ): this {
+    this.parameterCollectionFactory = parameterCollectionFactory;
+    return this;
+  }
+
+  public parseFunctions() {
+    const sut = new SharedFunctionsParser(
+      {
+        codeValidator: this.codeValidator,
+        wrapError: this.wrapError,
+        createParameter: this.parameterFactory,
+        createParameterCollection: this.parameterCollectionFactory,
+      },
+    );
+    return sut.parseFunctions(this.functions, this.syntax);
+  }
+}
+
+function expectEqualName(expected: FunctionData, actual: ISharedFunction): void {
+  expect(actual.name).to.equal(expected.name);
+}
+
+function expectEqualParameters(expected: FunctionData, actual: ISharedFunction): void {
+  const actualSimplifiedParameters = actual.parameters.all.map((parameter) => ({
+    name: parameter.name,
+    optional: parameter.isOptional,
+  }));
+  const expectedSimplifiedParameters = expected.parameters?.map((parameter) => ({
+    name: parameter.name,
+    optional: parameter.optional || false,
+  })) || [];
+  expect(expectedSimplifiedParameters).to.deep.equal(actualSimplifiedParameters, 'Unequal parameters');
+}
+
+function expectEqualFunctionWithInlineCode(
+  expected: CodeInstruction,
+  actual: ISharedFunction,
+): void {
+  expect(actual.body, `function "${actual.name}" has no body`);
+  expectCodeFunctionBody(actual.body);
+  expect(actual.body.code, `function "${actual.name}" has no code`);
+  expect(actual.body.code.execute).to.equal(expected.code);
+  expect(actual.body.code.revert).to.equal(expected.revertCode);
+}
+
+function expectEqualCalls(
+  expected: FunctionCallDataStub[],
+  actual: ISharedFunction,
+) {
+  expect(actual.body, `function "${actual.name}" has no body`);
+  expectCallsFunctionBody(actual.body);
+  expect(actual.body.calls, `function "${actual.name}" has no calls`);
+  const actualSimplifiedCalls = actual.body.calls
+    .map((call) => ({
+      function: call.functionName,
+      params: call.args.getAllParameterNames().map((name) => ({
+        name, value: call.args.getArgument(name).argumentValue,
+      })),
+    }));
+  const expectedSimplifiedCalls = expected
+    .map((call) => ({
+      function: call.function,
+      params: Object.keys(call.parameters).map((key) => (
+        { name: key, value: call.parameters[key] }
+      )),
+    }));
+  expect(actualSimplifiedCalls).to.deep.equal(expectedSimplifiedCalls, 'Unequal calls');
+}

tests/unit/application/Parser/Executable/Script/Compiler/ParameterNameTestRunner.ts

@@ -0,0 +1,54 @@
+import { describe, it, expect } from 'vitest';
+
+export function testParameterName(action: (parameterName: string) => string) {
+  describe('name', () => {
+    describe('sets as expected', () => {
+      // arrange
+      const expectedValues: readonly string[] = [
+        'lowercase',
+        'onlyLetters',
+        'l3tt3rsW1thNumb3rs',
+      ];
+      for (const expected of expectedValues) {
+        it(expected, () => {
+          // act
+          const value = action(expected);
+          // assert
+          expect(value).to.equal(expected);
+        });
+      }
+    });
+    describe('throws if invalid', () => {
+      // arrange
+      const testScenarios: readonly {
+        readonly description: string;
+        readonly value: string;
+        readonly expectedError: string;
+      }[] = [
+        {
+          description: 'empty Name',
+          value: '',
+          expectedError: 'missing parameter name',
+        },
+        {
+          description: 'has @',
+          value: 'b@d',
+          expectedError: 'parameter name must be alphanumeric but it was "b@d"',
+        },
+        {
+          description: 'has {',
+          value: 'b{a}d',
+          expectedError: 'parameter name must be alphanumeric but it was "b{a}d"',
+        },
+      ];
+      for (const { description, value, expectedError } of testScenarios) {
+        it(description, () => {
+          // act
+          const act = () => action(value);
+          // assert
+          expect(act).to.throw(expectedError);
+        });
+      }
+    });
+  });
+}

tests/unit/application/Parser/Executable/Script/Compiler/ScriptCompiler.spec.ts

@@ -0,0 +1,326 @@
+import { describe, it, expect } from 'vitest';
+import type { FunctionData } from '@/application/collections/';
+import { ScriptCompiler } from '@/application/Parser/Executable/Script/Compiler/ScriptCompiler';
+import type { ISharedFunctionsParser } from '@/application/Parser/Executable/Script/Compiler/Function/ISharedFunctionsParser';
+import type { FunctionCallCompiler } from '@/application/Parser/Executable/Script/Compiler/Function/Call/Compiler/FunctionCallCompiler';
+import { LanguageSyntaxStub } from '@tests/unit/shared/Stubs/LanguageSyntaxStub';
+import { createFunctionDataWithCode } from '@tests/unit/shared/Stubs/FunctionDataStub';
+import { FunctionCallCompilerStub } from '@tests/unit/shared/Stubs/FunctionCallCompilerStub';
+import { SharedFunctionsParserStub } from '@tests/unit/shared/Stubs/SharedFunctionsParserStub';
+import { SharedFunctionCollectionStub } from '@tests/unit/shared/Stubs/SharedFunctionCollectionStub';
+import { parseFunctionCalls } from '@/application/Parser/Executable/Script/Compiler/Function/Call/FunctionCallParser';
+import { FunctionCallDataStub } from '@tests/unit/shared/Stubs/FunctionCallDataStub';
+import type { ILanguageSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/ILanguageSyntax';
+import type { ICodeValidator } from '@/application/Parser/Executable/Script/Validation/ICodeValidator';
+import { CodeValidatorStub } from '@tests/unit/shared/Stubs/CodeValidatorStub';
+import { NoEmptyLines } from '@/application/Parser/Executable/Script/Validation/Rules/NoEmptyLines';
+import { CompiledCodeStub } from '@tests/unit/shared/Stubs/CompiledCodeStub';
+import { createScriptDataWithCall, createScriptDataWithCode } from '@tests/unit/shared/Stubs/ScriptDataStub';
+import type { ErrorWithContextWrapper } from '@/application/Parser/ContextualError';
+import { errorWithContextWrapperStub } from '@tests/unit/shared/Stubs/ErrorWithContextWrapperStub';
+import { ScriptCodeStub } from '@tests/unit/shared/Stubs/ScriptCodeStub';
+import type { ScriptCodeFactory } from '@/domain/Executables/Script/Code/ScriptCodeFactory';
+import { createScriptCodeFactoryStub } from '@tests/unit/shared/Stubs/ScriptCodeFactoryStub';
+import { itThrowsContextualError } from '@tests/unit/application/Parser/ContextualErrorTester';
+
+describe('ScriptCompiler', () => {
+  describe('canCompile', () => {
+    it('returns true if "call" is defined', () => {
+      // arrange
+      const sut = new ScriptCompilerBuilder()
+        .withEmptyFunctions()
+        .build();
+      const script = createScriptDataWithCall();
+      // act
+      const actual = sut.canCompile(script);
+      // assert
+      expect(actual).to.equal(true);
+    });
+    it('returns false if "call" is undefined', () => {
+      // arrange
+      const sut = new ScriptCompilerBuilder()
+        .withEmptyFunctions()
+        .build();
+      const script = createScriptDataWithCode();
+      // act
+      const actual = sut.canCompile(script);
+      // assert
+      expect(actual).to.equal(false);
+    });
+  });
+  describe('compile', () => {
+    it('throws if script does not have body', () => {
+      // arrange
+      const expectedError = 'Script does include any calls.';
+      const scriptData = createScriptDataWithCode();
+      const sut = new ScriptCompilerBuilder()
+        .withSomeFunctions()
+        .build();
+      // act
+      const act = () => sut.compile(scriptData);
+      // assert
+      expect(act).to.throw(expectedError);
+    });
+    describe('code construction', () => {
+      it('returns code from the factory', () => {
+        // arrange
+        const expectedCode = new ScriptCodeStub();
+        const scriptCodeFactory = () => expectedCode;
+        const sut = new ScriptCompilerBuilder()
+          .withSomeFunctions()
+          .withScriptCodeFactory(scriptCodeFactory)
+          .build();
+        // act
+        const actualCode = sut.compile(createScriptDataWithCall());
+        // assert
+        expect(actualCode).to.equal(expectedCode);
+      });
+      it('creates code correctly', () => {
+        // arrange
+        const expectedCode = 'expected-code';
+        const expectedRevertCode = 'expected-revert-code';
+        let actualCode: string | undefined;
+        let actualRevertCode: string | undefined;
+        const scriptCodeFactory = (code: string, revertCode: string) => {
+          actualCode = code;
+          actualRevertCode = revertCode;
+          return new ScriptCodeStub();
+        };
+        const call = new FunctionCallDataStub();
+        const script = createScriptDataWithCall(call);
+        const functions = [createFunctionDataWithCode().withName('existing-func')];
+        const compiledFunctions = new SharedFunctionCollectionStub();
+        const functionParserMock = new SharedFunctionsParserStub();
+        functionParserMock.setup(functions, compiledFunctions);
+        const callCompilerMock = new FunctionCallCompilerStub();
+        callCompilerMock.setup(
+          parseFunctionCalls(call),
+          compiledFunctions,
+          new CompiledCodeStub()
+            .withCode(expectedCode)
+            .withRevertCode(expectedRevertCode),
+        );
+        const sut = new ScriptCompilerBuilder()
+          .withFunctions(...functions)
+          .withSharedFunctionsParser(functionParserMock)
+          .withFunctionCallCompiler(callCompilerMock)
+          .withScriptCodeFactory(scriptCodeFactory)
+          .build();
+        // act
+        sut.compile(script);
+        // assert
+        expect(actualCode).to.equal(expectedCode);
+        expect(actualRevertCode).to.equal(expectedRevertCode);
+      });
+    });
+
+    describe('parses functions as expected', () => {
+      it('parses functions with expected syntax', () => {
+        // arrange
+        const expected: ILanguageSyntax = new LanguageSyntaxStub();
+        const parser = new SharedFunctionsParserStub();
+        const sut = new ScriptCompilerBuilder()
+          .withSomeFunctions()
+          .withSyntax(expected)
+          .withSharedFunctionsParser(parser)
+          .build();
+        const scriptData = createScriptDataWithCall();
+        // act
+        sut.compile(scriptData);
+        // assert
+        expect(parser.callHistory.length).to.equal(1);
+        expect(parser.callHistory[0].syntax).to.equal(expected);
+      });
+      it('parses given functions', () => {
+        // arrange
+        const expectedFunctions = [createFunctionDataWithCode().withName('existing-func')];
+        const parser = new SharedFunctionsParserStub();
+        const sut = new ScriptCompilerBuilder()
+          .withFunctions(...expectedFunctions)
+          .withSharedFunctionsParser(parser)
+          .build();
+        const scriptData = createScriptDataWithCall();
+        // act
+        sut.compile(scriptData);
+        // assert
+        expect(parser.callHistory.length).to.equal(1);
+        expect(parser.callHistory[0].functions).to.deep.equal(expectedFunctions);
+      });
+    });
+    describe('rethrows error with script name', () => {
+      // arrange
+      const scriptName = 'scriptName';
+      const expectedErrorMessage = `Failed to compile script: ${scriptName}`;
+      const expectedInnerError = new Error();
+      const callCompiler: FunctionCallCompiler = {
+        compileFunctionCalls: () => { throw expectedInnerError; },
+      };
+      const scriptData = createScriptDataWithCall()
+        .withName(scriptName);
+      const builder = new ScriptCompilerBuilder()
+        .withSomeFunctions()
+        .withFunctionCallCompiler(callCompiler);
+      itThrowsContextualError({
+        // act
+        throwingAction: (wrapError) => {
+          builder
+            .withErrorWrapper(wrapError)
+            .build()
+            .compile(scriptData);
+        },
+        // assert
+        expectedWrappedError: expectedInnerError,
+        expectedContextMessage: expectedErrorMessage,
+      });
+    });
+    describe('rethrows error from script code factory with script name', () => {
+      // arrange
+      const scriptName = 'scriptName';
+      const expectedErrorMessage = `Failed to compile script: ${scriptName}`;
+      const expectedInnerError = new Error();
+      const scriptCodeFactory: ScriptCodeFactory = () => {
+        throw expectedInnerError;
+      };
+      const scriptData = createScriptDataWithCall()
+        .withName(scriptName);
+      const builder = new ScriptCompilerBuilder()
+        .withSomeFunctions()
+        .withScriptCodeFactory(scriptCodeFactory);
+      itThrowsContextualError({
+        // act
+        throwingAction: (wrapError) => {
+          builder
+            .withErrorWrapper(wrapError)
+            .build()
+            .compile(scriptData);
+        },
+        // assert
+        expectedWrappedError: expectedInnerError,
+        expectedContextMessage: expectedErrorMessage,
+      });
+    });
+    it('validates compiled code as expected', () => {
+      // arrange
+      const expectedRules = [
+        NoEmptyLines,
+        // Allow duplicated lines to enable calling same function multiple times
+      ];
+      const expectedExecuteCode = 'execute code to be validated';
+      const expectedRevertCode = 'revert code to be validated';
+      const scriptData = createScriptDataWithCall();
+      const validator = new CodeValidatorStub();
+      const sut = new ScriptCompilerBuilder()
+        .withSomeFunctions()
+        .withCodeValidator(validator)
+        .withFunctionCallCompiler(
+          new FunctionCallCompilerStub()
+            .withDefaultCompiledCode(
+              new CompiledCodeStub()
+                .withCode(expectedExecuteCode)
+                .withRevertCode(expectedRevertCode),
+            ),
+        )
+        .build();
+      // act
+      sut.compile(scriptData);
+      // assert
+      validator.assertHistory({
+        validatedCodes: [expectedExecuteCode, expectedRevertCode],
+        rules: expectedRules,
+      });
+    });
+  });
+});
+
+class ScriptCompilerBuilder {
+  private static createFunctions(...names: string[]): FunctionData[] {
+    return names.map((functionName) => {
+      return createFunctionDataWithCode().withName(functionName);
+    });
+  }
+
+  private functions: FunctionData[] | undefined;
+
+  private syntax: ILanguageSyntax = new LanguageSyntaxStub();
+
+  private sharedFunctionsParser: ISharedFunctionsParser = new SharedFunctionsParserStub();
+
+  private callCompiler: FunctionCallCompiler = new FunctionCallCompilerStub();
+
+  private codeValidator: ICodeValidator = new CodeValidatorStub();
+
+  private wrapError: ErrorWithContextWrapper = errorWithContextWrapperStub;
+
+  private scriptCodeFactory: ScriptCodeFactory = createScriptCodeFactoryStub({
+    defaultCodePrefix: ScriptCompilerBuilder.name,
+  });
+
+  public withFunctions(...functions: FunctionData[]): this {
+    this.functions = functions;
+    return this;
+  }
+
+  public withSomeFunctions(): this {
+    this.functions = ScriptCompilerBuilder.createFunctions('test-function');
+    return this;
+  }
+
+  public withFunctionNames(...functionNames: string[]): this {
+    this.functions = ScriptCompilerBuilder.createFunctions(...functionNames);
+    return this;
+  }
+
+  public withEmptyFunctions(): this {
+    this.functions = [];
+    return this;
+  }
+
+  public withSyntax(syntax: ILanguageSyntax): this {
+    this.syntax = syntax;
+    return this;
+  }
+
+  public withSharedFunctionsParser(
+    sharedFunctionsParser: ISharedFunctionsParser,
+  ): this {
+    this.sharedFunctionsParser = sharedFunctionsParser;
+    return this;
+  }
+
+  public withCodeValidator(
+    codeValidator: ICodeValidator,
+  ): this {
+    this.codeValidator = codeValidator;
+    return this;
+  }
+
+  public withFunctionCallCompiler(callCompiler: FunctionCallCompiler): this {
+    this.callCompiler = callCompiler;
+    return this;
+  }
+
+  public withErrorWrapper(wrapError: ErrorWithContextWrapper): this {
+    this.wrapError = wrapError;
+    return this;
+  }
+
+  public withScriptCodeFactory(scriptCodeFactory: ScriptCodeFactory): this {
+    this.scriptCodeFactory = scriptCodeFactory;
+    return this;
+  }
+
+  public build(): ScriptCompiler {
+    if (!this.functions) {
+      throw new Error('Function behavior not defined');
+    }
+    return new ScriptCompiler(
+      this.functions,
+      this.syntax,
+      this.sharedFunctionsParser,
+      this.callCompiler,
+      this.codeValidator,
+      this.wrapError,
+      this.scriptCodeFactory,
+    );
+  }
+}

tests/unit/application/Parser/Executable/Script/ScriptParser.spec.ts

@@ -0,0 +1,512 @@
+import { describe, it, expect } from 'vitest';
+import type { ScriptData } from '@/application/collections/';
+import { parseScript, type ScriptFactory } from '@/application/Parser/Executable/Script/ScriptParser';
+import { type DocsParser } from '@/application/Parser/Executable/DocumentationParser';
+import { RecommendationLevel } from '@/domain/Executables/Script/RecommendationLevel';
+import { itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { ScriptCompilerStub } from '@tests/unit/shared/Stubs/ScriptCompilerStub';
+import { createScriptDataWithCall, createScriptDataWithCode, createScriptDataWithoutCallOrCodes } from '@tests/unit/shared/Stubs/ScriptDataStub';
+import { EnumParserStub } from '@tests/unit/shared/Stubs/EnumParserStub';
+import { ScriptCodeStub } from '@tests/unit/shared/Stubs/ScriptCodeStub';
+import { CategoryCollectionSpecificUtilitiesStub } from '@tests/unit/shared/Stubs/CategoryCollectionSpecificUtilitiesStub';
+import { LanguageSyntaxStub } from '@tests/unit/shared/Stubs/LanguageSyntaxStub';
+import type { IEnumParser } from '@/application/Common/Enum';
+import { NoEmptyLines } from '@/application/Parser/Executable/Script/Validation/Rules/NoEmptyLines';
+import { NoDuplicatedLines } from '@/application/Parser/Executable/Script/Validation/Rules/NoDuplicatedLines';
+import { CodeValidatorStub } from '@tests/unit/shared/Stubs/CodeValidatorStub';
+import type { ICodeValidator } from '@/application/Parser/Executable/Script/Validation/ICodeValidator';
+import type { ErrorWithContextWrapper } from '@/application/Parser/ContextualError';
+import { ErrorWrapperStub } from '@tests/unit/shared/Stubs/ErrorWrapperStub';
+import type { ExecutableValidatorFactory } from '@/application/Parser/Executable/Validation/ExecutableValidator';
+import { ExecutableValidatorStub, createExecutableValidatorFactoryStub } from '@tests/unit/shared/Stubs/ExecutableValidatorStub';
+import { ExecutableType } from '@/application/Parser/Executable/Validation/ExecutableType';
+import type { ScriptErrorContext } from '@/application/Parser/Executable/Validation/ExecutableErrorContext';
+import type { ScriptCodeFactory } from '@/domain/Executables/Script/Code/ScriptCodeFactory';
+import { createScriptCodeFactoryStub } from '@tests/unit/shared/Stubs/ScriptCodeFactoryStub';
+import { ScriptStub } from '@tests/unit/shared/Stubs/ScriptStub';
+import { createScriptFactorySpy } from '@tests/unit/shared/Stubs/ScriptFactoryStub';
+import { expectExists } from '@tests/shared/Assertions/ExpectExists';
+import { itThrowsContextualError } from '@tests/unit/application/Parser/ContextualErrorTester';
+import type { CategoryCollectionSpecificUtilities } from '@/application/Parser/Executable/CategoryCollectionSpecificUtilities';
+import { itAsserts, itValidatesDefinedData, itValidatesName } from '../Validation/ExecutableValidationTester';
+import { generateDataValidationTestScenarios } from '../Validation/DataValidationTestScenarioGenerator';
+
+describe('ScriptParser', () => {
+  describe('parseScript', () => {
+    it('parses name correctly', () => {
+      // arrange
+      const expected = 'test-expected-name';
+      const scriptData = createScriptDataWithCode()
+        .withName(expected);
+      const { scriptFactorySpy, getInitParameters } = createScriptFactorySpy();
+      // act
+      const actualScript = new TestContext()
+        .withData(scriptData)
+        .withScriptFactory(scriptFactorySpy)
+        .parseScript();
+      // assert
+      const actualName = getInitParameters(actualScript)?.name;
+      expect(actualName).to.equal(expected);
+    });
+    it('parses docs correctly', () => {
+      // arrange
+      const expectedDocs = ['https://expected-doc1.com', 'https://expected-doc2.com'];
+      const { scriptFactorySpy, getInitParameters } = createScriptFactorySpy();
+      const scriptData = createScriptDataWithCode()
+        .withDocs(expectedDocs);
+      const docsParser: DocsParser = (data) => data.docs as typeof expectedDocs;
+      // act
+      const actualScript = new TestContext()
+        .withData(scriptData)
+        .withScriptFactory(scriptFactorySpy)
+        .withDocsParser(docsParser)
+        .parseScript();
+      // assert
+      const actualDocs = getInitParameters(actualScript)?.docs;
+      expect(actualDocs).to.deep.equal(expectedDocs);
+    });
+    it('gets script from the factory', () => {
+      // arrange
+      const expectedScript = new ScriptStub('expected-script');
+      const scriptFactory: ScriptFactory = () => expectedScript;
+      // act
+      const actualScript = new TestContext()
+        .withScriptFactory(scriptFactory)
+        .parseScript();
+      // assert
+      expect(actualScript).to.equal(expectedScript);
+    });
+    describe('level', () => {
+      describe('generated `undefined` level if given absent value', () => {
+        itEachAbsentStringValue((absentValue) => {
+          // arrange
+          const expectedLevel = undefined;
+          const scriptData = createScriptDataWithCode()
+            .withRecommend(absentValue);
+          const { scriptFactorySpy, getInitParameters } = createScriptFactorySpy();
+          // act
+          const actualScript = new TestContext()
+            .withData(scriptData)
+            .withScriptFactory(scriptFactorySpy)
+            .parseScript();
+          // assert
+          const actualLevel = getInitParameters(actualScript)?.level;
+          expect(actualLevel).to.equal(expectedLevel);
+        }, { excludeNull: true });
+      });
+      it('parses level as expected', () => {
+        // arrange
+        const expectedLevel = RecommendationLevel.Standard;
+        const expectedName = 'level';
+        const levelText = 'standard';
+        const scriptData = createScriptDataWithCode()
+          .withRecommend(levelText);
+        const parserMock = new EnumParserStub<RecommendationLevel>()
+          .setup(expectedName, levelText, expectedLevel);
+        const { scriptFactorySpy, getInitParameters } = createScriptFactorySpy();
+        // act
+        const actualScript = new TestContext()
+          .withData(scriptData)
+          .withParser(parserMock)
+          .withScriptFactory(scriptFactorySpy)
+          .parseScript();
+        // assert
+        const actualLevel = getInitParameters(actualScript)?.level;
+        expect(actualLevel).to.equal(expectedLevel);
+      });
+    });
+    describe('code', () => {
+      it('creates from script code factory', () => {
+        // arrange
+        const expectedCode = new ScriptCodeStub();
+        const scriptCodeFactory: ScriptCodeFactory = () => expectedCode;
+        const { scriptFactorySpy, getInitParameters } = createScriptFactorySpy();
+        // act
+        const actualScript = new TestContext()
+          .withScriptCodeFactory(scriptCodeFactory)
+          .withScriptFactory(scriptFactorySpy)
+          .parseScript();
+        // assert
+        const actualCode = getInitParameters(actualScript)?.code;
+        expect(expectedCode).to.equal(actualCode);
+      });
+      describe('parses code correctly', () => {
+        it('parses "execute" as expected', () => {
+          // arrange
+          const expectedCode = 'expected-code';
+          let actualCode: string | undefined;
+          const scriptCodeFactory: ScriptCodeFactory = (code) => {
+            actualCode = code;
+            return new ScriptCodeStub();
+          };
+          const scriptData = createScriptDataWithCode()
+            .withCode(expectedCode);
+          // act
+          new TestContext()
+            .withData(scriptData)
+            .withScriptCodeFactory(scriptCodeFactory)
+            .parseScript();
+          // assert
+          expect(actualCode).to.equal(expectedCode);
+        });
+        it('parses "revert" as expected', () => {
+          // arrange
+          const expectedRevertCode = 'expected-revert-code';
+          const scriptData = createScriptDataWithCode()
+            .withRevertCode(expectedRevertCode);
+          let actualRevertCode: string | undefined;
+          const scriptCodeFactory: ScriptCodeFactory = (_, revertCode) => {
+            actualRevertCode = revertCode;
+            return new ScriptCodeStub();
+          };
+          // act
+          new TestContext()
+            .withData(scriptData)
+            .withScriptCodeFactory(scriptCodeFactory)
+            .parseScript();
+          // assert
+          expect(actualRevertCode).to.equal(expectedRevertCode);
+        });
+      });
+      describe('compiler', () => {
+        it('compiles the code through the compiler', () => {
+          // arrange
+          const expectedCode = new ScriptCodeStub();
+          const script = createScriptDataWithCode();
+          const compiler = new ScriptCompilerStub()
+            .withCompileAbility(script, expectedCode);
+          const collectionUtilities = new CategoryCollectionSpecificUtilitiesStub()
+            .withCompiler(compiler);
+          const { scriptFactorySpy, getInitParameters } = createScriptFactorySpy();
+          // act
+          const actualScript = new TestContext()
+            .withData(script)
+            .withCollectionUtilities(collectionUtilities)
+            .withScriptFactory(scriptFactorySpy)
+            .parseScript();
+          // assert
+          const actualCode = getInitParameters(actualScript)?.code;
+          expect(actualCode).to.equal(expectedCode);
+        });
+      });
+      describe('syntax', () => {
+        it('set from the context', () => { // tests through script validation logic
+          // arrange
+          const commentDelimiter = 'should not throw';
+          const duplicatedCode = `${commentDelimiter} duplicate-line\n${commentDelimiter} duplicate-line`;
+          const collectionUtilities = new CategoryCollectionSpecificUtilitiesStub()
+            .withSyntax(new LanguageSyntaxStub().withCommentDelimiters(commentDelimiter));
+          const script = createScriptDataWithoutCallOrCodes()
+            .withCode(duplicatedCode);
+          // act
+          const act = () => new TestContext()
+            .withData(script)
+            .withCollectionUtilities(collectionUtilities);
+          // assert
+          expect(act).to.not.throw();
+        });
+      });
+      describe('validates a expected', () => {
+        it('validates script with inline code (that is not compiled)', () => {
+          // arrange
+          const expectedRules = [
+            NoEmptyLines,
+            NoDuplicatedLines,
+          ];
+          const expectedCode = 'expected code to be validated';
+          const expectedRevertCode = 'expected revert code to be validated';
+          const expectedCodeCalls = [
+            expectedCode,
+            expectedRevertCode,
+          ];
+          const validator = new CodeValidatorStub();
+          const scriptCodeFactory = createScriptCodeFactoryStub({
+            scriptCode: new ScriptCodeStub()
+              .withExecute(expectedCode)
+              .withRevert(expectedRevertCode),
+          });
+          // act
+          new TestContext()
+            .withScriptCodeFactory(scriptCodeFactory)
+            .withCodeValidator(validator)
+            .parseScript();
+          // assert
+          validator.assertHistory({
+            validatedCodes: expectedCodeCalls,
+            rules: expectedRules,
+          });
+        });
+        it('does not validate compiled code', () => {
+          // arrange
+          const expectedRules = [];
+          const expectedCodeCalls = [];
+          const validator = new CodeValidatorStub();
+          const script = createScriptDataWithCall();
+          const compiler = new ScriptCompilerStub()
+            .withCompileAbility(script, new ScriptCodeStub());
+          const collectionUtilities = new CategoryCollectionSpecificUtilitiesStub()
+            .withCompiler(compiler);
+          // act
+          new TestContext()
+            .withData(script)
+            .withCodeValidator(validator)
+            .withCollectionUtilities(collectionUtilities)
+            .parseScript();
+          // assert
+          validator.assertHistory({
+            validatedCodes: expectedCodeCalls,
+            rules: expectedRules,
+          });
+        });
+      });
+    });
+    describe('validation', () => {
+      describe('validates for name', () => {
+        // arrange
+        const expectedName = 'expected script name to be validated';
+        const script = createScriptDataWithCall()
+          .withName(expectedName);
+        const expectedContext: ScriptErrorContext = {
+          type: ExecutableType.Script,
+          self: script,
+        };
+        itValidatesName((validatorFactory) => {
+          // act
+          new TestContext()
+            .withData(script)
+            .withValidatorFactory(validatorFactory)
+            .parseScript();
+          // assert
+          return {
+            expectedNameToValidate: expectedName,
+            expectedErrorContext: expectedContext,
+          };
+        });
+      });
+      describe('validates for defined data', () => {
+        // arrange
+        const expectedScript = createScriptDataWithCall();
+        const expectedContext: ScriptErrorContext = {
+          type: ExecutableType.Script,
+          self: expectedScript,
+        };
+        itValidatesDefinedData(
+          (validatorFactory) => {
+            // act
+            new TestContext()
+              .withData(expectedScript)
+              .withValidatorFactory(validatorFactory)
+              .parseScript();
+            // assert
+            return {
+              expectedDataToValidate: expectedScript,
+              expectedErrorContext: expectedContext,
+            };
+          },
+        );
+      });
+      describe('validates data', () => {
+        // arrange
+        const testScenarios = generateDataValidationTestScenarios<ScriptData>(
+          {
+            assertErrorMessage: 'Neither "call" or "code" is defined.',
+            expectFail: [{
+              description: 'with no call or code',
+              data: createScriptDataWithoutCallOrCodes(),
+            }],
+            expectPass: [
+              {
+                description: 'with call',
+                data: createScriptDataWithCall(),
+              },
+              {
+                description: 'with code',
+                data: createScriptDataWithCode(),
+              },
+            ],
+          },
+          {
+            assertErrorMessage: 'Both "call" and "revertCode" are defined.',
+            expectFail: [{
+              description: 'with both call and revertCode',
+              data: createScriptDataWithCall()
+                .withRevertCode('revert-code'),
+            }],
+            expectPass: [
+              {
+                description: 'with call, without revertCode',
+                data: createScriptDataWithCall()
+                  .withRevertCode(undefined),
+              },
+              {
+                description: 'with revertCode, without call',
+                data: createScriptDataWithCode()
+                  .withRevertCode('revert code'),
+              },
+            ],
+          },
+          {
+            assertErrorMessage: 'Both "call" and "code" are defined.',
+            expectFail: [{
+              description: 'with both call and code',
+              data: createScriptDataWithCall()
+                .withCode('code'),
+            }],
+            expectPass: [
+              {
+                description: 'with call, without code',
+                data: createScriptDataWithCall()
+                  .withCode(''),
+              },
+              {
+                description: 'with code, without call',
+                data: createScriptDataWithCode()
+                  .withCode('code'),
+              },
+            ],
+          },
+        );
+        testScenarios.forEach(({
+          description, expectedPass, data: scriptData, expectedMessage,
+        }) => {
+          describe(description, () => {
+            itAsserts({
+              expectedConditionResult: expectedPass,
+              test: (validatorFactory) => {
+                const expectedContext: ScriptErrorContext = {
+                  type: ExecutableType.Script,
+                  self: scriptData,
+                };
+                // act
+                new TestContext()
+                  .withData(scriptData)
+                  .withValidatorFactory(validatorFactory)
+                  .parseScript();
+                // assert
+                expectExists(expectedMessage);
+                return {
+                  expectedErrorMessage: expectedMessage,
+                  expectedErrorContext: expectedContext,
+                };
+              },
+            });
+          });
+        });
+      });
+    });
+    describe('rethrows exception if script factory fails', () => {
+      // arrange
+      const givenData = createScriptDataWithCode();
+      const expectedContextMessage = 'Failed to parse script.';
+      const expectedError = new Error();
+      const validatorFactory: ExecutableValidatorFactory = () => {
+        const validatorStub = new ExecutableValidatorStub();
+        validatorStub.createContextualErrorMessage = (message) => message;
+        return validatorStub;
+      };
+      // act & assert
+      itThrowsContextualError({
+        throwingAction: (wrapError) => {
+          const factoryMock: ScriptFactory = () => {
+            throw expectedError;
+          };
+          new TestContext()
+            .withScriptFactory(factoryMock)
+            .withErrorWrapper(wrapError)
+            .withValidatorFactory(validatorFactory)
+            .withData(givenData)
+            .parseScript();
+        },
+        expectedWrappedError: expectedError,
+        expectedContextMessage,
+      });
+    });
+  });
+});
+
+class TestContext {
+  private data: ScriptData = createScriptDataWithCode();
+
+  private collectionUtilities
+  : CategoryCollectionSpecificUtilities = new CategoryCollectionSpecificUtilitiesStub();
+
+  private levelParser: IEnumParser<RecommendationLevel> = new EnumParserStub<RecommendationLevel>()
+    .setupDefaultValue(RecommendationLevel.Standard);
+
+  private scriptFactory: ScriptFactory = createScriptFactorySpy().scriptFactorySpy;
+
+  private codeValidator: ICodeValidator = new CodeValidatorStub();
+
+  private errorWrapper: ErrorWithContextWrapper = new ErrorWrapperStub().get();
+
+  private validatorFactory: ExecutableValidatorFactory = createExecutableValidatorFactoryStub;
+
+  private docsParser: DocsParser = () => ['docs'];
+
+  private scriptCodeFactory: ScriptCodeFactory = createScriptCodeFactoryStub({
+    defaultCodePrefix: TestContext.name,
+  });
+
+  public withCodeValidator(codeValidator: ICodeValidator): this {
+    this.codeValidator = codeValidator;
+    return this;
+  }
+
+  public withData(data: ScriptData): this {
+    this.data = data;
+    return this;
+  }
+
+  public withCollectionUtilities(
+    collectionUtilities: CategoryCollectionSpecificUtilities,
+  ): this {
+    this.collectionUtilities = collectionUtilities;
+    return this;
+  }
+
+  public withParser(parser: IEnumParser<RecommendationLevel>): this {
+    this.levelParser = parser;
+    return this;
+  }
+
+  public withScriptFactory(scriptFactory: ScriptFactory): this {
+    this.scriptFactory = scriptFactory;
+    return this;
+  }
+
+  public withValidatorFactory(validatorFactory: ExecutableValidatorFactory): this {
+    this.validatorFactory = validatorFactory;
+    return this;
+  }
+
+  public withErrorWrapper(errorWrapper: ErrorWithContextWrapper): this {
+    this.errorWrapper = errorWrapper;
+    return this;
+  }
+
+  public withScriptCodeFactory(scriptCodeFactory: ScriptCodeFactory): this {
+    this.scriptCodeFactory = scriptCodeFactory;
+    return this;
+  }
+
+  public withDocsParser(docsParser: DocsParser): this {
+    this.docsParser = docsParser;
+    return this;
+  }
+
+  public parseScript(): ReturnType<typeof parseScript> {
+    return parseScript(
+      this.data,
+      this.collectionUtilities,
+      {
+        levelParser: this.levelParser,
+        createScript: this.scriptFactory,
+        codeValidator: this.codeValidator,
+        wrapError: this.errorWrapper,
+        createValidator: this.validatorFactory,
+        createCode: this.scriptCodeFactory,
+        parseDocs: this.docsParser,
+      },
+    );
+  }
+}

tests/unit/application/Parser/Executable/Script/Validation/CodeValidator.spec.ts

@@ -0,0 +1,168 @@
+import { describe, it, expect } from 'vitest';
+import { CodeValidator } from '@/application/Parser/Executable/Script/Validation/CodeValidator';
+import { CodeValidationRuleStub } from '@tests/unit/shared/Stubs/CodeValidationRuleStub';
+import { itEachAbsentCollectionValue, itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { itIsSingletonFactory } from '@tests/unit/shared/TestCases/SingletonFactoryTests';
+import type { ICodeLine } from '@/application/Parser/Executable/Script/Validation/ICodeLine';
+import type { ICodeValidationRule, IInvalidCodeLine } from '@/application/Parser/Executable/Script/Validation/ICodeValidationRule';
+
+describe('CodeValidator', () => {
+  describe('instance', () => {
+    itIsSingletonFactory({
+      getter: () => CodeValidator.instance,
+      expectedType: CodeValidator,
+    });
+  });
+  describe('throwIfInvalid', () => {
+    describe('does not throw if code is absent', () => {
+      itEachAbsentStringValue((absentValue) => {
+        // arrange
+        const code = absentValue;
+        const sut = new CodeValidator();
+        // act
+        const act = () => sut.throwIfInvalid(code, [new CodeValidationRuleStub()]);
+        // assert
+        expect(act).to.not.throw();
+      }, { excludeNull: true, excludeUndefined: true });
+    });
+    describe('throws if rules are empty', () => {
+      itEachAbsentCollectionValue<ICodeValidationRule>((absentValue) => {
+        // arrange
+        const expectedError = 'missing rules';
+        const rules = absentValue;
+        const sut = new CodeValidator();
+        // act
+        const act = () => sut.throwIfInvalid('code', rules);
+        // assert
+        expect(act).to.throw(expectedError);
+      }, { excludeUndefined: true, excludeNull: true });
+    });
+    describe('splits lines as expected', () => {
+      it('supports all line separators', () => {
+        // arrange
+        const expectedLineTexts = ['line1', 'line2', 'line3', 'line4'];
+        const code = 'line1\r\nline2\rline3\nline4';
+        const spy = new CodeValidationRuleStub();
+        const sut = new CodeValidator();
+        // act
+        sut.throwIfInvalid(code, [spy]);
+        // expect
+        expect(spy.receivedLines).has.lengthOf(1);
+        const actualLineTexts = spy.receivedLines[0].map((line) => line.text);
+        expect(actualLineTexts).to.deep.equal(expectedLineTexts);
+      });
+      it('uses 1-indexed line numbering', () => {
+        // arrange
+        const expectedIndexes = [1, 2, 3];
+        const code = ['line1', 'line2', 'line3'].join('\n');
+        const spy = new CodeValidationRuleStub();
+        const sut = new CodeValidator();
+        // act
+        sut.throwIfInvalid(code, [spy]);
+        // expect
+        expect(spy.receivedLines).has.lengthOf(1);
+        const actualLineIndexes = spy.receivedLines[0].map((line) => line.index);
+        expect(actualLineIndexes).to.deep.equal(expectedIndexes);
+      });
+      it('matches texts with indexes as expected', () => {
+        // arrange
+        const expected: readonly ICodeLine[] = [
+          { index: 1, text: 'first' },
+          { index: 2, text: 'second' },
+        ];
+        const code = expected.map((line) => line.text).join('\n');
+        const spy = new CodeValidationRuleStub();
+        const sut = new CodeValidator();
+        // act
+        sut.throwIfInvalid(code, [spy]);
+        // expect
+        expect(spy.receivedLines).has.lengthOf(1);
+        expect(spy.receivedLines[0]).to.deep.equal(expected);
+      });
+    });
+    describe('throws invalid lines as expected', () => {
+      it('throws with invalid line from single rule', () => {
+        // arrange
+        const errorText = 'error';
+        const expectedError = new ExpectedErrorBuilder()
+          .withOkLine('line1')
+          .withErrorLine('line2', errorText)
+          .withOkLine('line3')
+          .withOkLine('line4')
+          .buildError();
+        const code = ['line1', 'line2', 'line3', 'line4'].join('\n');
+        const invalidLines: readonly IInvalidCodeLine[] = [
+          { index: 2, error: errorText },
+        ];
+        const rule = new CodeValidationRuleStub()
+          .withReturnValue(invalidLines);
+        const noopRule = new CodeValidationRuleStub()
+          .withReturnValue([]);
+        const sut = new CodeValidator();
+        // act
+        const act = () => sut.throwIfInvalid(code, [rule, noopRule]);
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+      it('throws with combined invalid lines from multiple rules', () => {
+        // arrange
+        const firstError = 'firstError';
+        const secondError = 'firstError';
+        const expectedError = new ExpectedErrorBuilder()
+          .withOkLine('line1')
+          .withErrorLine('line2', firstError)
+          .withOkLine('line3')
+          .withErrorLine('line4', secondError)
+          .buildError();
+        const code = ['line1', 'line2', 'line3', 'line4'].join('\n');
+        const firstRuleError: readonly IInvalidCodeLine[] = [
+          { index: 2, error: firstError },
+        ];
+        const secondRuleError: readonly IInvalidCodeLine[] = [
+          { index: 4, error: secondError },
+        ];
+        const firstRule = new CodeValidationRuleStub().withReturnValue(firstRuleError);
+        const secondRule = new CodeValidationRuleStub().withReturnValue(secondRuleError);
+        const sut = new CodeValidator();
+        // act
+        const act = () => sut.throwIfInvalid(code, [firstRule, secondRule]);
+        // assert
+        expect(act).to.throw(expectedError);
+      });
+    });
+  });
+});
+
+class ExpectedErrorBuilder {
+  private lineCount = 0;
+
+  private outputLines = new Array<string>();
+
+  public withOkLine(text: string) {
+    return this.withNumberedLine(`✅ ${text}`);
+  }
+
+  public withErrorLine(text: string, error: string) {
+    return this
+      .withNumberedLine(`❌ ${text}`)
+      .withLine(`\t⟶ ${error}`);
+  }
+
+  public buildError(): string {
+    return [
+      'Errors with the code.',
+      ...this.outputLines,
+    ].join('\n');
+  }
+
+  private withLine(line: string) {
+    this.outputLines.push(line);
+    return this;
+  }
+
+  private withNumberedLine(text: string) {
+    this.lineCount += 1;
+    const lineNumber = `[${this.lineCount}]`;
+    return this.withLine(`${lineNumber} ${text}`);
+  }
+}

tests/unit/application/Parser/Executable/Script/Validation/Rules/CodeValidationRuleTestRunner.ts

@@ -0,0 +1,36 @@
+import { it, expect } from 'vitest';
+import type { ICodeValidationRule, IInvalidCodeLine } from '@/application/Parser/Executable/Script/Validation/ICodeValidationRule';
+import type { ICodeLine } from '@/application/Parser/Executable/Script/Validation/ICodeLine';
+
+interface ICodeValidationRuleTestCase {
+  testName: string;
+  codeLines: readonly string[];
+  expected: readonly IInvalidCodeLine[];
+  sut: ICodeValidationRule;
+}
+
+export function testCodeValidationRule(testCases: readonly ICodeValidationRuleTestCase[]) {
+  for (const testCase of testCases) {
+    it(testCase.testName, () => {
+      // arrange
+      const { sut } = testCase;
+      const codeLines = createCodeLines(testCase.codeLines);
+      // act
+      const actual = sut.analyze(codeLines);
+      // assert
+      function sort(lines: readonly IInvalidCodeLine[]) { // To ignore order
+        return Array.from(lines).sort((a, b) => a.index - b.index);
+      }
+      expect(sort(actual)).to.deep.equal(sort(testCase.expected));
+    });
+  }
+}
+
+function createCodeLines(lines: readonly string[]): ICodeLine[] {
+  return lines.map((lineText, index): ICodeLine => (
+    {
+      index: index + 1,
+      text: lineText,
+    }
+  ));
+}

tests/unit/application/Parser/Executable/Script/Validation/Rules/NoDuplicatedLines.spec.ts

@@ -0,0 +1,78 @@
+import { describe } from 'vitest';
+import { NoDuplicatedLines } from '@/application/Parser/Executable/Script/Validation/Rules/NoDuplicatedLines';
+import { LanguageSyntaxStub } from '@tests/unit/shared/Stubs/LanguageSyntaxStub';
+import type { IInvalidCodeLine } from '@/application/Parser/Executable/Script/Validation/ICodeValidationRule';
+import { testCodeValidationRule } from './CodeValidationRuleTestRunner';
+
+describe('NoDuplicatedLines', () => {
+  describe('analyze', () => {
+    testCodeValidationRule([
+      {
+        testName: 'no results when code is valid',
+        codeLines: ['unique1', 'unique2', 'unique3', 'unique4'],
+        expected: [],
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()),
+      },
+      {
+        testName: 'detects single duplicated line as expected',
+        codeLines: ['duplicate', 'duplicate', 'unique', 'duplicate'],
+        expected: expectInvalidCodeLines([1, 2, 4]),
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()),
+      },
+      {
+        testName: 'detects multiple duplicated lines as expected',
+        codeLines: ['duplicate1', 'duplicate2', 'unique', 'duplicate1', 'unique2', 'duplicate2'],
+        expected: expectInvalidCodeLines([1, 4], [2, 6]),
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()),
+      },
+      {
+        testName: 'common code parts: does not detect multiple common code part usages as duplicates',
+        codeLines: ['good', 'good', 'bad', 'bad', 'good', 'also-good', 'also-good', 'unique'],
+        expected: expectInvalidCodeLines([3, 4]),
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()
+          .withCommonCodeParts('good', 'also-good')),
+      },
+      {
+        testName: 'common code parts: does not detect multiple common code part used in same code line as duplicates',
+        codeLines: ['bad', 'bad', 'good1 good2', 'good1 good2', 'good2 good1', 'good2 good1'],
+        expected: expectInvalidCodeLines([1, 2]),
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()
+          .withCommonCodeParts('good2', 'good1')),
+      },
+      {
+        testName: 'common code parts: detects when common code parts used in conjunction with unique words',
+        codeLines: [
+          'common-part1', 'common-part1', 'common-part1 common-part2', 'common-part1 unique', 'common-part1 unique',
+          'common-part2', 'common-part2 common-part1', 'unique common-part2', 'unique common-part2',
+        ],
+        expected: expectInvalidCodeLines([4, 5], [8, 9]),
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()
+          .withCommonCodeParts('common-part1', 'common-part2')),
+      },
+      {
+        testName: 'comments: does not when lines start with comment',
+        codeLines: ['#abc', '#abc', 'abc', 'unique', 'abc', '//abc', '//abc', '//unique', '#unique'],
+        expected: expectInvalidCodeLines([3, 5]),
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()
+          .withCommentDelimiters('#', '//')),
+      },
+      {
+        testName: 'comments: does when comments come after lien start',
+        codeLines: ['test #comment', 'test #comment', 'test2 # comment', 'test2 # comment'],
+        expected: expectInvalidCodeLines([1, 2], [3, 4]),
+        sut: new NoDuplicatedLines(new LanguageSyntaxStub()
+          .withCommentDelimiters('#')),
+      },
+    ]);
+  });
+});
+
+function expectInvalidCodeLines(
+  ...lines: readonly ReadonlyArray<number>[]
+): IInvalidCodeLine[] {
+  return lines.flatMap((occurrenceIndices): readonly IInvalidCodeLine[] => occurrenceIndices
+    .map((index): IInvalidCodeLine => ({
+      index,
+      error: `Line is duplicated at line numbers ${occurrenceIndices.join(',')}.`,
+    })));
+}

tests/unit/application/Parser/Executable/Script/Validation/Rules/NoEmptyLines.spec.ts

@@ -0,0 +1,46 @@
+import { describe } from 'vitest';
+import { NoEmptyLines } from '@/application/Parser/Executable/Script/Validation/Rules/NoEmptyLines';
+import { testCodeValidationRule } from './CodeValidationRuleTestRunner';
+
+describe('NoEmptyLines', () => {
+  describe('analyze', () => {
+    testCodeValidationRule([
+      {
+        testName: 'no results when code is valid',
+        codeLines: ['non-empty-line1', 'none-empty-line2'],
+        expected: [],
+        sut: new NoEmptyLines(),
+      },
+      {
+        testName: 'shows error for empty line',
+        codeLines: ['first line', '', 'third line'],
+        expected: [{ index: 2, error: 'Empty line' }],
+        sut: new NoEmptyLines(),
+      },
+      {
+        testName: 'shows error for multiple empty lines',
+        codeLines: ['first line', '', 'third line', ''],
+        expected: [2, 4].map((index) => ({ index, error: 'Empty line' })),
+        sut: new NoEmptyLines(),
+      },
+      {
+        testName: 'shows error for whitespace-only lines',
+        codeLines: ['first line', '  ', 'third line'],
+        expected: [{ index: 2, error: 'Empty line: "{whitespace}{whitespace}"' }],
+        sut: new NoEmptyLines(),
+      },
+      {
+        testName: 'shows error for tab-only lines',
+        codeLines: ['first line', '\t\t', 'third line'],
+        expected: [{ index: 2, error: 'Empty line: "{tab}{tab}"' }],
+        sut: new NoEmptyLines(),
+      },
+      {
+        testName: 'shows error for lines that consists of whitespace and tabs',
+        codeLines: ['first line', '\t \t', 'third line', ' \t '],
+        expected: [{ index: 2, error: 'Empty line: "{tab}{whitespace}{tab}"' }, { index: 4, error: 'Empty line: "{whitespace}{tab}{whitespace}"' }],
+        sut: new NoEmptyLines(),
+      },
+    ]);
+  });
+});

tests/unit/application/Parser/Executable/Script/Validation/Syntax/ConcreteSyntaxes.spec.ts

@@ -0,0 +1,31 @@
+import { describe, it, expect } from 'vitest';
+import { ShellScriptSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/ShellScriptSyntax';
+import type { ILanguageSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/ILanguageSyntax';
+import { BatchFileSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/BatchFileSyntax';
+
+function getSystemsUnderTest(): ILanguageSyntax[] {
+  return [new BatchFileSyntax(), new ShellScriptSyntax()];
+}
+
+describe('ConcreteSyntaxes', () => {
+  describe('commentDelimiters', () => {
+    for (const sut of getSystemsUnderTest()) {
+      it(`${sut.constructor.name} returns defined value`, () => {
+        // act
+        const value = sut.commentDelimiters;
+        // assert
+        expect(value);
+      });
+    }
+  });
+  describe('commonCodeParts', () => {
+    for (const sut of getSystemsUnderTest()) {
+      it(`${sut.constructor.name} returns defined value`, () => {
+        // act
+        const value = sut.commonCodeParts;
+        // assert
+        expect(value);
+      });
+    }
+  });
+});

tests/unit/application/Parser/Executable/Script/Validation/Syntax/SyntaxFactory.spec.ts

@@ -0,0 +1,14 @@
+import { describe } from 'vitest';
+import { SyntaxFactory } from '@/application/Parser/Executable/Script/Validation/Syntax/SyntaxFactory';
+import { ScriptingLanguage } from '@/domain/ScriptingLanguage';
+import { ShellScriptSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/ShellScriptSyntax';
+import { ScriptingLanguageFactoryTestRunner } from '@tests/unit/application/Common/ScriptingLanguage/ScriptingLanguageFactoryTestRunner';
+import { BatchFileSyntax } from '@/application/Parser/Executable/Script/Validation/Syntax/BatchFileSyntax';
+
+describe('SyntaxFactory', () => {
+  const sut = new SyntaxFactory();
+  const runner = new ScriptingLanguageFactoryTestRunner()
+    .expectInstance(ScriptingLanguage.shellscript, ShellScriptSyntax)
+    .expectInstance(ScriptingLanguage.batchfile, BatchFileSyntax);
+  runner.testCreateMethod(sut);
+});

tests/unit/application/Parser/Executable/Validation/DataValidationTestScenarioGenerator.ts

@@ -0,0 +1,36 @@
+export interface DataValidationTestScenario<T> {
+  readonly description: string;
+  readonly data: T;
+  readonly expectedPass: boolean;
+  readonly expectedMessage?: string;
+}
+
+export function generateDataValidationTestScenarios<T>(
+  ...conditionBasedScenarios: DataValidationConditionBasedTestScenario<T>[]
+): DataValidationTestScenario<T>[] {
+  return conditionBasedScenarios.flatMap((conditionScenario) => [
+    conditionScenario.expectFail.map((failDefinition): DataValidationTestScenario<T> => ({
+      description: `fails: "${failDefinition.description}"`,
+      data: failDefinition.data,
+      expectedPass: false,
+      expectedMessage: conditionScenario.assertErrorMessage,
+    })),
+    conditionScenario.expectPass.map((passDefinition): DataValidationTestScenario<T> => ({
+      description: `passes: "${passDefinition.description}"`,
+      data: passDefinition.data,
+      expectedPass: true,
+      expectedMessage: conditionScenario.assertErrorMessage,
+    })),
+  ].flat());
+}
+
+interface DataValidationConditionBasedTestScenario<T> {
+  readonly assertErrorMessage?: string;
+  readonly expectPass: readonly DataValidationScenarioDefinition<T>[];
+  readonly expectFail: readonly DataValidationScenarioDefinition<T>[];
+}
+
+interface DataValidationScenarioDefinition<T> {
+  readonly description: string;
+  readonly data: T;
+}

tests/unit/application/Parser/Executable/Validation/ExecutableValidationTester.ts

@@ -0,0 +1,218 @@
+import { it } from 'vitest';
+import type { ExecutableValidator, ExecutableValidatorFactory } from '@/application/Parser/Executable/Validation/ExecutableValidator';
+import type { ExecutableErrorContext } from '@/application/Parser/Executable/Validation/ExecutableErrorContext';
+import { ExecutableValidatorStub } from '@tests/unit/shared/Stubs/ExecutableValidatorStub';
+import { expectExists } from '@tests/shared/Assertions/ExpectExists';
+import type { ExecutableData } from '@/application/collections/';
+import type { FunctionKeys } from '@/TypeHelpers';
+import { formatAssertionMessage } from '@tests/shared/FormatAssertionMessage';
+import { indentText } from '@tests/shared/Text';
+
+type ValidationTestFunction<TExpectation> = (
+  factory: ExecutableValidatorFactory,
+) => TExpectation;
+
+interface ValidNameExpectation {
+  readonly expectedNameToValidate: string;
+  readonly expectedErrorContext: ExecutableErrorContext;
+}
+
+export function itValidatesName(
+  test: ValidationTestFunction<ValidNameExpectation>,
+) {
+  it('validates for name', () => {
+    // arrange
+    const validator = new ExecutableValidatorStub();
+    const factoryStub: ExecutableValidatorFactory = () => validator;
+    // act
+    test(factoryStub);
+    // assert
+    const call = validator.callHistory.find((c) => c.methodName === 'assertValidName');
+    expectExists(call);
+  });
+  it('validates for name with correct name', () => {
+    // arrange
+    const validator = new ExecutableValidatorStub();
+    const factoryStub: ExecutableValidatorFactory = () => validator;
+    // act
+    const expectation = test(factoryStub);
+    // assert
+    const expectedName = expectation.expectedNameToValidate;
+    const names = validator.callHistory
+      .filter((c) => c.methodName === 'assertValidName')
+      .flatMap((c) => c.args[0]);
+    expect(names).to.include(expectedName);
+  });
+  it('validates for name with correct context', () => {
+    expectCorrectContextForFunctionCall({
+      methodName: 'assertValidName',
+      act: test,
+      expectContext: (expectation) => expectation.expectedErrorContext,
+    });
+  });
+}
+
+interface ValidDataExpectation {
+  readonly expectedDataToValidate: ExecutableData;
+  readonly expectedErrorContext: ExecutableErrorContext;
+}
+
+export function itValidatesDefinedData(
+  test: ValidationTestFunction<ValidDataExpectation>,
+) {
+  it('validates data', () => {
+    // arrange
+    const validator = new ExecutableValidatorStub();
+    const factoryStub: ExecutableValidatorFactory = () => validator;
+    // act
+    test(factoryStub);
+    // assert
+    const call = validator.callHistory.find((c) => c.methodName === 'assertDefined');
+    expectExists(call);
+  });
+  it('validates data with correct data', () => {
+    // arrange
+    const validator = new ExecutableValidatorStub();
+    const factoryStub: ExecutableValidatorFactory = () => validator;
+    // act
+    const expectation = test(factoryStub);
+    // assert
+    const expectedData = expectation.expectedDataToValidate;
+    const calls = validator.callHistory.filter((c) => c.methodName === 'assertDefined');
+    const names = calls.flatMap((c) => c.args[0]);
+    expect(names).to.include(expectedData);
+  });
+  it('validates data with correct context', () => {
+    expectCorrectContextForFunctionCall({
+      methodName: 'assertDefined',
+      act: test,
+      expectContext: (expectation) => expectation.expectedErrorContext,
+    });
+  });
+}
+
+interface AssertionExpectation {
+  readonly expectedErrorMessage: string;
+  readonly expectedErrorContext: ExecutableErrorContext;
+}
+
+export function itAsserts(
+  testScenario: {
+    readonly test: ValidationTestFunction<AssertionExpectation>,
+    readonly expectedConditionResult: boolean;
+  },
+) {
+  it('asserts with correct message', () => {
+    // arrange
+    const validator = new ExecutableValidatorStub()
+      .withAssertThrowsOnFalseCondition(false);
+    const factoryStub: ExecutableValidatorFactory = () => validator;
+    // act
+    const expectation = testScenario.test(factoryStub);
+    // assert
+    const expectedError = expectation.expectedErrorMessage;
+    const calls = validator.callHistory.filter((c) => c.methodName === 'assert');
+    const actualMessages = calls.map((call) => {
+      const [, message] = call.args;
+      return message;
+    });
+    expect(actualMessages).to.include(expectedError, formatAssertionMessage([
+      'Assertion failed: The expected error message was not triggered.',
+      `Expected: "${expectedError}"`,
+      'Actual messages (none match expected):',
+      indentText(actualMessages.map((message) => `- ${message}`).join('\n')),
+    ]));
+  });
+  it('asserts with correct context', () => {
+    expectCorrectContextForFunctionCall({
+      methodName: 'assert',
+      act: testScenario.test,
+      expectContext: (expectation) => expectation.expectedErrorContext,
+    });
+  });
+  it('asserts with correct condition result', () => {
+    // arrange
+    const expectedEvaluationResult = testScenario.expectedConditionResult;
+    const validator = new ExecutableValidatorStub()
+      .withAssertThrowsOnFalseCondition(false);
+    const factoryStub: ExecutableValidatorFactory = () => validator;
+    // act
+    const expectation = testScenario.test(factoryStub);
+    // assert
+    const assertCalls = validator.callHistory
+      .filter((call) => call.methodName === 'assert');
+    expect(assertCalls).to.have.length.greaterThan(0);
+    const assertCallsWithMessage = assertCalls
+      .filter((call) => {
+        const [, message] = call.args;
+        return message === expectation.expectedErrorMessage;
+      });
+    expect(assertCallsWithMessage).to.have.length.greaterThan(0);
+    const evaluationResults = assertCallsWithMessage
+      .map((call) => {
+        const [predicate] = call.args;
+        return predicate as (() => boolean);
+      })
+      .map((predicate) => predicate());
+    expect(evaluationResults).to.include(expectedEvaluationResult);
+  });
+}
+
+function expectCorrectContextForFunctionCall<T>(testScenario: {
+  methodName: FunctionKeys<ExecutableValidator>,
+  act: ValidationTestFunction<T>,
+  expectContext: (actionResult: T) => ExecutableErrorContext,
+}) {
+  // arrange
+  const { methodName } = testScenario;
+  const createdValidators = new Array<{
+    readonly validator: ExecutableValidatorStub;
+    readonly context: ExecutableErrorContext;
+  }>();
+  const factoryStub: ExecutableValidatorFactory = (context) => {
+    const validator = new ExecutableValidatorStub()
+      .withAssertThrowsOnFalseCondition(false);
+    createdValidators.push(({
+      validator,
+      context,
+    }));
+    return validator;
+  };
+  // act
+  const actionResult = testScenario.act(factoryStub);
+  // assert
+  const expectedContext = testScenario.expectContext(actionResult);
+  const providedContexts = createdValidators
+    .filter((v) => v.validator.callHistory.find((c) => c.methodName === methodName))
+    .map((v) => v.context);
+  expectDeepIncludes( // to.deep.include is not working
+    providedContexts,
+    expectedContext,
+    formatAssertionMessage([
+      'Error context mismatch.',
+      'Provided contexts do not include the expected context.',
+      'Expected context:',
+      indentText(JSON.stringify(expectedContext, undefined, 2)),
+      'Provided contexts:',
+      indentText(JSON.stringify(providedContexts, undefined, 2)),
+    ]),
+  );
+}
+
+function expectDeepIncludes<T>(
+  array: readonly T[],
+  item: T,
+  message: string,
+) {
+  const serializeItem = (c) => JSON.stringify(c);
+  const serializedContexts = array.map((c) => serializeItem(c));
+  const serializedExpectedContext = serializeItem(item);
+  expect(serializedContexts).to.include(serializedExpectedContext, formatAssertionMessage([
+    'Error context mismatch.',
+    'Provided contexts do not include the expected context.',
+    'Expected context:',
+    indentText(JSON.stringify(message, undefined, 2)),
+    'Provided contexts:',
+    indentText(JSON.stringify(message, undefined, 2)),
+  ]));
+}

tests/unit/application/Parser/Executable/Validation/ExecutableValidator.spec.ts

@@ -0,0 +1,242 @@
+import { describe, it, expect } from 'vitest';
+import { CategoryDataStub } from '@tests/unit/shared/Stubs/CategoryDataStub';
+import type { ExecutableData } from '@/application/collections/';
+import { createExecutableErrorContextStub } from '@tests/unit/shared/Stubs/ExecutableErrorContextStub';
+import type { ExecutableErrorContext } from '@/application/Parser/Executable/Validation/ExecutableErrorContext';
+import { collectExceptionMessage } from '@tests/unit/shared/ExceptionCollector';
+import { ContextualExecutableValidator, createExecutableDataValidator, type ExecutableValidator } from '@/application/Parser/Executable/Validation/ExecutableValidator';
+import type { ExecutableContextErrorMessageCreator } from '@/application/Parser/Executable/Validation/ExecutableErrorContextMessage';
+import { getAbsentObjectTestCases, getAbsentStringTestCases } from '@tests/unit/shared/TestCases/AbsentTests';
+
+describe('createExecutableDataValidator', () => {
+  it(`returns an instance of ${ContextualExecutableValidator.name}`, () => {
+    // arrange
+    const context = createExecutableErrorContextStub();
+    // act
+    const validator = createExecutableDataValidator(context);
+    // assert
+    expect(validator).to.be.instanceOf(ContextualExecutableValidator);
+  });
+});
+
+describe('ContextualExecutableValidator', () => {
+  describe('assertValidName', () => {
+    describe('throws when name is invalid', () => {
+      // arrange
+      const testScenarios: readonly {
+        readonly description: string;
+        readonly invalidName: unknown;
+        readonly expectedMessage: string;
+      }[] = [
+        ...getAbsentStringTestCases().map((testCase) => ({
+          description: `missing name (${testCase.valueName})`,
+          invalidName: testCase.absentValue,
+          expectedMessage: 'missing name',
+        })),
+        {
+          description: 'invalid type',
+          invalidName: 33,
+          expectedMessage: 'Name (33) is not a string but number.',
+        },
+      ];
+      testScenarios.forEach(({ description, invalidName, expectedMessage }) => {
+        describe(`given "${description}"`, () => {
+          itThrowsCorrectly({
+            // act
+            throwingAction: (sut) => {
+              sut.assertValidName(invalidName as string);
+            },
+            // assert
+            expectedMessage,
+          });
+        });
+      });
+    });
+    it('does not throw when name is valid', () => {
+      // arrange
+      const validName = 'validName';
+      const sut = new ValidatorBuilder()
+        .build();
+      // act
+      const act = () => sut.assertValidName(validName);
+      // assert
+      expect(act).to.not.throw();
+    });
+  });
+  describe('assertDefined', () => {
+    describe('throws when data is missing', () => {
+      // arrange
+      const testScenarios: readonly {
+        readonly description: string;
+        readonly invalidData: unknown;
+      }[] = [
+        ...getAbsentObjectTestCases().map((testCase) => ({
+          description: `absent object (${testCase.valueName})`,
+          invalidData: testCase.absentValue,
+        })),
+        {
+          description: 'empty object',
+          invalidData: {},
+        },
+      ];
+      testScenarios.forEach(({ description, invalidData }) => {
+        describe(`given "${description}"`, () => {
+          const expectedMessage = 'missing executable data';
+          itThrowsCorrectly({
+            // act
+            throwingAction: (sut: ExecutableValidator) => {
+              sut.assertDefined(invalidData as ExecutableData);
+            },
+            // assert
+            expectedMessage,
+          });
+        });
+      });
+    });
+    it('does not throw if data is defined', () => {
+      // arrange
+      const data = new CategoryDataStub();
+      const sut = new ValidatorBuilder()
+        .build();
+      // act
+      const act = () => sut.assertDefined(data);
+      // assert
+      expect(act).to.not.throw();
+    });
+  });
+  describe('assert', () => {
+    describe('throws if validation fails', () => {
+      const falsePredicate = () => false;
+      const expectedErrorMessage = 'expected error';
+      // assert
+      itThrowsCorrectly({
+        // act
+        throwingAction: (sut: ExecutableValidator) => {
+          sut.assert(falsePredicate, expectedErrorMessage);
+        },
+        // assert
+        expectedMessage: expectedErrorMessage,
+      });
+    });
+    it('does not throw if validation succeeds', () => {
+      // arrange
+      const truePredicate = () => true;
+      const sut = new ValidatorBuilder()
+        .build();
+      // act
+      const act = () => sut.assert(truePredicate, 'ignored error');
+      // assert
+      expect(act).to.not.throw();
+    });
+  });
+  describe('createContextualErrorMessage', () => {
+    it('creates using the correct error message', () => {
+      // arrange
+      const expectedErrorMessage = 'expected error';
+      const errorMessageBuilder: ExecutableContextErrorMessageCreator = (message) => message;
+      const sut = new ValidatorBuilder()
+        .withErrorMessageCreator(errorMessageBuilder)
+        .build();
+      // act
+      const actualErrorMessage = sut.createContextualErrorMessage(expectedErrorMessage);
+      // assert
+      expect(actualErrorMessage).to.equal(expectedErrorMessage);
+    });
+    it('creates using the correct context', () => {
+      // arrange
+      const expectedContext = createExecutableErrorContextStub();
+      let actualContext: ExecutableErrorContext | undefined;
+      const errorMessageBuilder: ExecutableContextErrorMessageCreator = (_, context) => {
+        actualContext = context;
+        return '';
+      };
+      const sut = new ValidatorBuilder()
+        .withContext(expectedContext)
+        .withErrorMessageCreator(errorMessageBuilder)
+        .build();
+      // act
+      sut.createContextualErrorMessage('unimportant');
+      // assert
+      expect(actualContext).to.equal(expectedContext);
+    });
+  });
+});
+
+type ValidationThrowingFunction = (
+  sut: ContextualExecutableValidator,
+) => void;
+
+interface ValidationThrowingTestScenario {
+  readonly throwingAction: ValidationThrowingFunction,
+  readonly expectedMessage: string;
+}
+
+function itThrowsCorrectly(
+  testScenario: ValidationThrowingTestScenario,
+): void {
+  it('throws an error', () => {
+    // arrange
+    const expectedErrorMessage = 'Injected error message';
+    const errorMessageBuilder: ExecutableContextErrorMessageCreator = () => expectedErrorMessage;
+    const sut = new ValidatorBuilder()
+      .withErrorMessageCreator(errorMessageBuilder)
+      .build();
+    // act
+    const action = () => testScenario.throwingAction(sut);
+    // assert
+    expect(action).to.throw();
+  });
+  it('throws with the correct error message', () => {
+    // arrange
+    const expectedErrorMessage = testScenario.expectedMessage;
+    const errorMessageBuilder: ExecutableContextErrorMessageCreator = (message) => message;
+    const sut = new ValidatorBuilder()
+      .withErrorMessageCreator(errorMessageBuilder)
+      .build();
+    // act
+    const action = () => testScenario.throwingAction(sut);
+    // assert
+    const actualErrorMessage = collectExceptionMessage(action);
+    expect(actualErrorMessage).to.equal(expectedErrorMessage);
+  });
+  it('throws with the correct context', () => {
+    // arrange
+    const expectedContext = createExecutableErrorContextStub();
+    const serializeContext = (context: ExecutableErrorContext) => JSON.stringify(context);
+    const errorMessageBuilder:
+    ExecutableContextErrorMessageCreator = (_, context) => serializeContext(context);
+    const sut = new ValidatorBuilder()
+      .withContext(expectedContext)
+      .withErrorMessageCreator(errorMessageBuilder)
+      .build();
+    // act
+    const action = () => testScenario.throwingAction(sut);
+    // assert
+    const expectedSerializedContext = serializeContext(expectedContext);
+    const actualSerializedContext = collectExceptionMessage(action);
+    expect(expectedSerializedContext).to.equal(actualSerializedContext);
+  });
+}
+
+class ValidatorBuilder {
+  private errorContext: ExecutableErrorContext = createExecutableErrorContextStub();
+
+  private errorMessageCreator: ExecutableContextErrorMessageCreator = () => `[${ValidatorBuilder.name}] stub error message`;
+
+  public withErrorMessageCreator(errorMessageCreator: ExecutableContextErrorMessageCreator): this {
+    this.errorMessageCreator = errorMessageCreator;
+    return this;
+  }
+
+  public withContext(errorContext: ExecutableErrorContext): this {
+    this.errorContext = errorContext;
+    return this;
+  }
+
+  public build(): ContextualExecutableValidator {
+    return new ContextualExecutableValidator(
+      this.errorContext,
+      this.errorMessageCreator,
+    );
+  }
+}