From b210aaddf26629179f77fe19f62f65d8a0ca2b87 Mon Sep 17 00:00:00 2001
From: undergroundwires <git@undergroundwires.dev>
Date: Thu, 16 Dec 2021 02:40:56 +0100
Subject: [PATCH] Improve script/category name validation

- Use better error messages with more context.
- Unify their validation logic and share tests.
- Validate also type of the name.
- Refactor node (Script/Category) parser tests for easier future
  changes and cleaner test code (using `TestBuilder` to do dirty work in
  unified way).
- Add more tests. Custom `Error` properties are compared manually due to
  `chai` not supporting deep equality checks (chaijs/chai#1065,
  chaijs/chai#1405).
---
 src/application/Parser/CategoryParser.ts      | 131 +++++++---
 .../Parser/NodeValidation/NodeData.ts         |   3 +
 .../Parser/NodeValidation/NodeDataError.ts    |  35 +++
 .../Parser/NodeValidation/NodeType.ts         |   4 +
 .../Parser/NodeValidation/NodeValidator.ts    |  38 +++
 src/application/Parser/Script/ScriptParser.ts |  60 +++--
 src/domain/Script.ts                          |   2 +-
 .../application/Parser/CategoryParser.spec.ts | 235 ++++++++++++++----
 .../NodeValidation/NodeDataError.spec.ts      |  67 +++++
 .../NodeValidation/NodeValidator.spec.ts      | 100 ++++++++
 .../NodeValidation/NodeValidatorTestRunner.ts |  87 +++++++
 .../Parser/Script/ScriptParser.spec.ts        | 205 ++++++++++-----
 tests/unit/domain/Script.spec.ts              |   4 +-
 .../shared/Assertions/ExpectThrowsError.ts    |  50 ++++
 tests/unit/shared/Stubs/EnumParserStub.ts     |   4 +-
 .../shared/Stubs/NodeDataErrorContextStub.ts  |  12 +
 tests/unit/shared/TestCases/AbsentTests.ts    |  16 +-
 17 files changed, 857 insertions(+), 196 deletions(-)
 create mode 100644 src/application/Parser/NodeValidation/NodeData.ts
 create mode 100644 src/application/Parser/NodeValidation/NodeDataError.ts
 create mode 100644 src/application/Parser/NodeValidation/NodeType.ts
 create mode 100644 src/application/Parser/NodeValidation/NodeValidator.ts
 create mode 100644 tests/unit/application/Parser/NodeValidation/NodeDataError.spec.ts
 create mode 100644 tests/unit/application/Parser/NodeValidation/NodeValidator.spec.ts
 create mode 100644 tests/unit/application/Parser/NodeValidation/NodeValidatorTestRunner.ts
 create mode 100644 tests/unit/shared/Assertions/ExpectThrowsError.ts
 create mode 100644 tests/unit/shared/Stubs/NodeDataErrorContextStub.ts

diff --git a/src/application/Parser/CategoryParser.ts b/src/application/Parser/CategoryParser.ts
index d602415a..a83fd830 100644
--- a/src/application/Parser/CategoryParser.ts
+++ b/src/application/Parser/CategoryParser.ts
@@ -3,6 +3,8 @@ import type {
 } from '@/application/collections/';
 import { Script } from '@/domain/Script';
 import { Category } from '@/domain/Category';
+import { NodeValidator } from '@/application/Parser/NodeValidation/NodeValidator';
+import { NodeType } from '@/application/Parser/NodeValidation/NodeType';
 import { parseDocUrls } from './DocumentationParser';
 import { ICategoryCollectionParseContext } from './Script/ICategoryCollectionParseContext';
 import { parseScript } from './Script/ScriptParser';
@@ -12,35 +14,67 @@ let categoryIdCounter = 0;
 export function parseCategory(
   category: CategoryData,
   context: ICategoryCollectionParseContext,
+  factory: CategoryFactoryType = CategoryFactory,
 ): Category {
   if (!context) { throw new Error('missing context'); }
-  ensureValid(category);
+  return parseCategoryRecursively({
+    categoryData: category,
+    context,
+    factory,
+  });
+}
+
+interface ICategoryParseContext {
+  readonly categoryData: CategoryData,
+  readonly context: ICategoryCollectionParseContext,
+  readonly factory: CategoryFactoryType,
+  readonly parentCategory?: CategoryData,
+}
+// eslint-disable-next-line consistent-return
+function parseCategoryRecursively(context: ICategoryParseContext): Category {
+  ensureValidCategory(context.categoryData, context.parentCategory);
   const children: ICategoryChildren = {
     subCategories: new Array<Category>(),
     subScripts: new Array<Script>(),
   };
-  for (const data of category.children) {
-    parseCategoryChild(data, children, category, context);
+  for (const data of context.categoryData.children) {
+    parseNode({
+      nodeData: data,
+      children,
+      parent: context.categoryData,
+      factory: context.factory,
+      context: context.context,
+    });
+  }
+  try {
+    return context.factory(
+      /* id: */ categoryIdCounter++,
+      /* name: */ context.categoryData.category,
+      /* docs: */ parseDocUrls(context.categoryData),
+      /* categories: */ children.subCategories,
+      /* scripts: */ children.subScripts,
+    );
+  } catch (err) {
+    new NodeValidator({
+      type: NodeType.Category,
+      selfNode: context.categoryData,
+      parentNode: context.parentCategory,
+    }).throw(err.message);
   }
-  return new Category(
-    /* id: */ categoryIdCounter++,
-    /* name: */ category.category,
-    /* docs: */ parseDocUrls(category),
-    /* categories: */ children.subCategories,
-    /* scripts: */ children.subScripts,
-  );
 }
 
-function ensureValid(category: CategoryData) {
-  if (!category) {
-    throw Error('missing category');
-  }
-  if (!category.children || category.children.length === 0) {
-    throw Error(`category has no children: "${category.category}"`);
-  }
-  if (!category.category || category.category.length === 0) {
-    throw Error('category has no name');
-  }
+function ensureValidCategory(category: CategoryData, parentCategory?: CategoryData) {
+  new NodeValidator({
+    type: NodeType.Category,
+    selfNode: category,
+    parentNode: parentCategory,
+  })
+    .assertDefined(category)
+    .assertValidName(category.category)
+    .assert(
+      () => category.children && category.children.length > 0,
+      `"${category.category}" has no children.`,
+    );
 }
 
 interface ICategoryChildren {
@@ -48,22 +82,29 @@ interface ICategoryChildren {
   subScripts: Script[];
 }
 
-function parseCategoryChild(
-  data: CategoryOrScriptData,
-  children: ICategoryChildren,
-  parent: CategoryData,
-  context: ICategoryCollectionParseContext,
-) {
-  if (isCategory(data)) {
-    const subCategory = parseCategory(data as CategoryData, context);
-    children.subCategories.push(subCategory);
-  } else if (isScript(data)) {
-    const scriptData = data as ScriptData;
-    const script = parseScript(scriptData, context);
-    children.subScripts.push(script);
+interface INodeParseContext {
+  readonly nodeData: CategoryOrScriptData;
+  readonly children: ICategoryChildren;
+  readonly parent: CategoryData;
+  readonly factory: CategoryFactoryType;
+  readonly context: ICategoryCollectionParseContext;
+}
+function parseNode(context: INodeParseContext) {
+  const validator = new NodeValidator({ selfNode: context.nodeData, parentNode: context.parent });
+  validator.assertDefined(context.nodeData);
+  if (isCategory(context.nodeData)) {
+    const subCategory = parseCategoryRecursively({
+      categoryData: context.nodeData as CategoryData,
+      context: context.context,
+      factory: context.factory,
+      parentCategory: context.parent,
+    });
+    context.children.subCategories.push(subCategory);
+  } else if (isScript(context.nodeData)) {
+    const script = parseScript(context.nodeData as ScriptData, context.context);
+    context.children.subScripts.push(script);
   } else {
-    throw new Error(`Child element is neither a category or a script.
-                Parent: ${parent.category}, element: ${JSON.stringify(data)}`);
+    validator.throw('Node is neither a category or a script.');
   }
 }
 
@@ -73,14 +114,22 @@ function isScript(data: CategoryOrScriptData): data is ScriptData {
 }
 
 function isCategory(data: CategoryOrScriptData): data is CategoryData {
-  const { category } = data as CategoryData;
-  return category && category.length > 0;
+  return hasProperty(data, 'category');
 }
 
-function hasCode(holder: InstructionHolder): boolean {
-  return holder.code && holder.code.length > 0;
+function hasCode(data: InstructionHolder): boolean {
+  return hasProperty(data, 'code');
 }
 
-function hasCall(holder: InstructionHolder) {
-  return holder.call !== undefined;
+function hasCall(data: InstructionHolder) {
+  return hasProperty(data, 'call');
 }
+
+function hasProperty(object: unknown, propertyName: string) {
+  return Object.prototype.hasOwnProperty.call(object, propertyName);
+}
+
+export type CategoryFactoryType = (
+  ...parameters: ConstructorParameters<typeof Category>) => Category;
+
+const CategoryFactory: CategoryFactoryType = (...parameters) => new Category(...parameters);
diff --git a/src/application/Parser/NodeValidation/NodeData.ts b/src/application/Parser/NodeValidation/NodeData.ts
new file mode 100644
index 00000000..1b12dc69
--- /dev/null
+++ b/src/application/Parser/NodeValidation/NodeData.ts
@@ -0,0 +1,3 @@
+import type { ScriptData, CategoryData } from '@/application/collections/';
+
+export type NodeData = CategoryData | ScriptData;
diff --git a/src/application/Parser/NodeValidation/NodeDataError.ts b/src/application/Parser/NodeValidation/NodeDataError.ts
new file mode 100644
index 00000000..03242508
--- /dev/null
+++ b/src/application/Parser/NodeValidation/NodeDataError.ts
@@ -0,0 +1,35 @@
+import { NodeType } from './NodeType';
+import { NodeData } from './NodeData';
+
+export class NodeDataError extends Error {
+  constructor(message: string, public readonly context: INodeDataErrorContext) {
+    super(createMessage(message, context));
+    Object.setPrototypeOf(this, new.target.prototype); // https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-2.html#support-for-newtarget
+    this.name = new.target.name;
+  }
+}
+
+export interface INodeDataErrorContext {
+  readonly type?: NodeType;
+  readonly selfNode: NodeData;
+  readonly parentNode?: NodeData;
+}
+
+function createMessage(errorMessage: string, context: INodeDataErrorContext) {
+  let message = '';
+  if (context.type !== undefined) {
+    message += `${NodeType[context.type]}: `;
+  }
+  message += errorMessage;
+  message += `\n${dump(context)}`;
+  return message;
+}
+
+function dump(context: INodeDataErrorContext): string {
+  const printJson = (obj: unknown) => JSON.stringify(obj, undefined, 2);
+  let output = `Self: ${printJson(context.selfNode)}`;
+  if (context.parentNode) {
+    output += `\nParent: ${printJson(context.parentNode)}`;
+  }
+  return output;
+}
diff --git a/src/application/Parser/NodeValidation/NodeType.ts b/src/application/Parser/NodeValidation/NodeType.ts
new file mode 100644
index 00000000..648db72d
--- /dev/null
+++ b/src/application/Parser/NodeValidation/NodeType.ts
@@ -0,0 +1,4 @@
+export enum NodeType {
+  Script,
+  Category,
+}
diff --git a/src/application/Parser/NodeValidation/NodeValidator.ts b/src/application/Parser/NodeValidation/NodeValidator.ts
new file mode 100644
index 00000000..0fce365c
--- /dev/null
+++ b/src/application/Parser/NodeValidation/NodeValidator.ts
@@ -0,0 +1,38 @@
+import { INodeDataErrorContext, NodeDataError } from './NodeDataError';
+import { NodeData } from './NodeData';
+
+export class NodeValidator {
+  constructor(private readonly context: INodeDataErrorContext) {
+
+  }
+
+  public assertValidName(nameValue: string) {
+    return this
+      .assert(
+        () => Boolean(nameValue),
+        'missing name',
+      )
+      .assert(
+        () => typeof nameValue === 'string',
+        `Name (${JSON.stringify(nameValue)}) is not a string but ${typeof nameValue}.`,
+      );
+  }
+
+  public assertDefined(node: NodeData) {
+    return this.assert(
+      () => node !== undefined && node !== null && Object.keys(node).length > 0,
+      'missing node data',
+    );
+  }
+
+  public assert(validationPredicate: () => boolean, errorMessage: string) {
+    if (!validationPredicate()) {
+      this.throw(errorMessage);
+    }
+    return this;
+  }
+
+  public throw(errorMessage: string) {
+    throw new NodeDataError(errorMessage, this.context);
+  }
+}
diff --git a/src/application/Parser/Script/ScriptParser.ts b/src/application/Parser/Script/ScriptParser.ts
index b68c2c2a..9bdee0cd 100644
--- a/src/application/Parser/Script/ScriptParser.ts
+++ b/src/application/Parser/Script/ScriptParser.ts
@@ -5,22 +5,31 @@ import { IScriptCode } from '@/domain/IScriptCode';
 import { ScriptCode } from '@/domain/ScriptCode';
 import { parseDocUrls } from '../DocumentationParser';
 import { createEnumParser, IEnumParser } from '../../Common/Enum';
+import { NodeType } from '../NodeValidation/NodeType';
+import { NodeValidator } from '../NodeValidation/NodeValidator';
 import { ICategoryCollectionParseContext } from './ICategoryCollectionParseContext';
 
+// eslint-disable-next-line consistent-return
 export function parseScript(
   data: ScriptData,
   context: ICategoryCollectionParseContext,
   levelParser = createEnumParser(RecommendationLevel),
+  scriptFactory: ScriptFactoryType = ScriptFactory,
 ): Script {
-  validateScript(data);
+  const validator = new NodeValidator({ type: NodeType.Script, selfNode: data });
+  validateScript(data, validator);
   if (!context) { throw new Error('missing context'); }
-  const script = new Script(
-    /* name: */ data.name,
-    /* code: */ parseCode(data, context),
-    /* docs: */ parseDocUrls(data),
-    /* level: */ parseLevel(data.recommend, levelParser),
-  );
-  return script;
+  try {
+    const script = scriptFactory(
+      /* name: */ data.name,
+      /* code: */ parseCode(data, context),
+      /* docs: */ parseDocUrls(data),
+      /* level: */ parseLevel(data.recommend, levelParser),
+    );
+    return script;
+  } catch (err) {
+    validator.throw(err.message);
+  }
 }
 
 function parseLevel(
@@ -40,21 +49,24 @@ function parseCode(script: ScriptData, context: ICategoryCollectionParseContext)
   return new ScriptCode(script.code, script.revertCode, context.syntax);
 }
 
-function ensureNotBothCallAndCode(script: ScriptData) {
-  if (script.code && script.call) {
-    throw new Error('cannot define both "call" and "code"');
-  }
-  if (script.revertCode && script.call) {
-    throw new Error('cannot define "revertCode" if "call" is defined');
-  }
+function validateScript(script: ScriptData, validator: NodeValidator) {
+  validator
+    .assertDefined(script)
+    .assertValidName(script.name)
+    .assert(
+      () => Boolean(script.code || script.call),
+      'Must define either "call" or "code".',
+    )
+    .assert(
+      () => !(script.code && script.call),
+      'Cannot define both "call" and "code".',
+    )
+    .assert(
+      () => !(script.revertCode && script.call),
+      'Cannot define "revertCode" if "call" is defined.',
+    );
 }
 
-function validateScript(script: ScriptData) {
-  if (!script) {
-    throw new Error('missing script');
-  }
-  if (!script.code && !script.call) {
-    throw new Error('must define either "call" or "code"');
-  }
-  ensureNotBothCallAndCode(script);
-}
+export type ScriptFactoryType = (...parameters: ConstructorParameters<typeof Script>) => Script;
+
+const ScriptFactory: ScriptFactoryType = (...parameters) => new Script(...parameters);
diff --git a/src/domain/Script.ts b/src/domain/Script.ts
index 67ccd1b1..1e65c7e2 100644
--- a/src/domain/Script.ts
+++ b/src/domain/Script.ts
@@ -12,7 +12,7 @@ export class Script extends BaseEntity<string> implements IScript {
   ) {
     super(name);
     if (!code) {
-      throw new Error(`missing code (script: ${name})`);
+      throw new Error('missing code');
     }
     validateLevel(level);
   }
diff --git a/tests/unit/application/Parser/CategoryParser.spec.ts b/tests/unit/application/Parser/CategoryParser.spec.ts
index 075bb011..3e9d0004 100644
--- a/tests/unit/application/Parser/CategoryParser.spec.ts
+++ b/tests/unit/application/Parser/CategoryParser.spec.ts
@@ -1,6 +1,7 @@
 import 'mocha';
 import { expect } from 'chai';
-import { parseCategory } from '@/application/Parser/CategoryParser';
+import type { CategoryData, CategoryOrScriptData } from '@/application/collections/';
+import { CategoryFactoryType, parseCategory } from '@/application/Parser/CategoryParser';
 import { parseScript } from '@/application/Parser/Script/ScriptParser';
 import { parseDocUrls } from '@/application/Parser/DocumentationParser';
 import { ScriptCompilerStub } from '@tests/unit/shared/Stubs/ScriptCompilerStub';
@@ -8,50 +9,136 @@ import { ScriptDataStub } from '@tests/unit/shared/Stubs/ScriptDataStub';
 import { CategoryCollectionParseContextStub } from '@tests/unit/shared/Stubs/CategoryCollectionParseContextStub';
 import { LanguageSyntaxStub } from '@tests/unit/shared/Stubs/LanguageSyntaxStub';
 import { CategoryDataStub } from '@tests/unit/shared/Stubs/CategoryDataStub';
-import { itEachAbsentCollectionValue, itEachAbsentObjectValue, itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { itEachAbsentCollectionValue, itEachAbsentObjectValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { NodeType } from '@/application/Parser/NodeValidation/NodeType';
+import { expectThrowsNodeError, ITestScenario, NodeValidationTestRunner } from '@tests/unit/application/Parser/NodeValidation/NodeValidatorTestRunner';
+import { ICategoryCollectionParseContext } from '@/application/Parser/Script/ICategoryCollectionParseContext';
+import { Category } from '@/domain/Category';
 
 describe('CategoryParser', () => {
   describe('parseCategory', () => {
-    describe('invalid category', () => {
-      describe('throws when category data is absent', () => {
-        itEachAbsentObjectValue((absentValue) => {
-          // arrange
-          const expectedMessage = 'missing category';
-          const category = absentValue;
-          const context = new CategoryCollectionParseContextStub();
-          // act
-          const act = () => parseCategory(category, context);
-          // assert
-          expect(act).to.throw(expectedMessage);
+    describe('invalid category data', () => {
+      describe('validates script data', () => {
+        describe('satisfies shared node tests', () => {
+          new NodeValidationTestRunner()
+            .testInvalidNodeName((invalidName) => {
+              return createTest(
+                new CategoryDataStub().withName(invalidName),
+              );
+            })
+            .testMissingNodeData((node) => {
+              return createTest(node as CategoryData);
+            });
         });
+        describe('throws when category children is absent', () => {
+          itEachAbsentCollectionValue((absentValue) => {
+            // arrange
+            const categoryName = 'test';
+            const expectedMessage = `"${categoryName}" has no children.`;
+            const category = new CategoryDataStub()
+              .withName(categoryName)
+              .withChildren(absentValue);
+            // act
+            const test = createTest(category);
+            // assert
+            expectThrowsNodeError(test, expectedMessage);
+          });
+        });
+        describe('throws when category child is missing', () => {
+          new NodeValidationTestRunner()
+            .testMissingNodeData((missingNode) => {
+              // arrange
+              const invalidChildNode = missingNode;
+              const parent = new CategoryDataStub()
+                .withName('parent')
+                .withChildren([new CategoryDataStub().withName('valid child'), invalidChildNode]);
+              return ({
+                // act
+                act: () => new TestBuilder()
+                  .withData(parent)
+                  .parseCategory(),
+                // assert
+                expectedContext: {
+                  selfNode: invalidChildNode,
+                  parentNode: parent,
+                },
+              });
+            });
+        });
+        it('throws when node is neither a category or a script', () => {
+          // arrange
+          const expectedError = 'Node is neither a category or a script.';
+          const invalidChildNode = { property: 'non-empty-value' } as never as CategoryOrScriptData;
+          const parent = new CategoryDataStub()
+            .withName('parent')
+            .withChildren([new CategoryDataStub().withName('valid child'), invalidChildNode]);
+          // act
+          const test: ITestScenario = {
+            // act
+            act: () => new TestBuilder()
+              .withData(parent)
+              .parseCategory(),
+            // assert
+            expectedContext: {
+              selfNode: invalidChildNode,
+              parentNode: parent,
+            },
+          };
+          // assert
+          expectThrowsNodeError(test, expectedError);
+        });
+        describe('throws when category child is invalid category', () => {
+          new NodeValidationTestRunner().testInvalidNodeName((invalidName) => {
+            // arrange
+            const invalidChildNode = new CategoryDataStub()
+              .withName(invalidName);
+            const parent = new CategoryDataStub()
+              .withName('parent')
+              .withChildren([new CategoryDataStub().withName('valid child'), invalidChildNode]);
+            return ({
+              // act
+              act: () => new TestBuilder()
+                .withData(parent)
+                .parseCategory(),
+              // assert
+              expectedContext: {
+                type: NodeType.Category,
+                selfNode: invalidChildNode,
+                parentNode: parent,
+              },
+            });
+          });
+        });
+        function createTest(category: CategoryData): ITestScenario {
+          return {
+            act: () => new TestBuilder()
+              .withData(category)
+              .parseCategory(),
+            expectedContext: {
+              type: NodeType.Category,
+              selfNode: category,
+            },
+          };
+        }
       });
-      describe('throws when category children is absent', () => {
-        itEachAbsentCollectionValue((absentValue) => {
-          // arrange
-          const categoryName = 'test';
-          const expectedMessage = `category has no children: "${categoryName}"`;
-          const category = new CategoryDataStub()
-            .withName(categoryName)
-            .withChildren(absentValue);
-          const context = new CategoryCollectionParseContextStub();
-          // act
-          const act = () => parseCategory(category, context);
-          // assert
-          expect(act).to.throw(expectedMessage);
-        });
-      });
-      describe('throws when name is absent', () => {
-        itEachAbsentStringValue((absentValue) => {
-          // arrange
-          const expectedMessage = 'category has no name';
-          const category = new CategoryDataStub()
-            .withName(absentValue);
-          const context = new CategoryCollectionParseContextStub();
-          // act
-          const act = () => parseCategory(category, context);
-          // assert
-          expect(act).to.throw(expectedMessage);
-        });
+      it(`rethrows exception if ${Category.name} cannot be constructed`, () => {
+        // arrange
+        const expectedError = 'category creation failed';
+        const factoryMock: CategoryFactoryType = () => { throw new Error(expectedError); };
+        const data = new CategoryDataStub();
+        // act
+        const act = () => new TestBuilder()
+          .withData(data)
+          .withFactory(factoryMock)
+          .parseCategory();
+        // expect
+        expectThrowsNodeError({
+          act,
+          expectedContext: {
+            type: NodeType.Category,
+            selfNode: data,
+          },
+        }, expectedError);
       });
     });
     describe('throws when context is absent', () => {
@@ -59,9 +146,10 @@ describe('CategoryParser', () => {
         // arrange
         const expectedError = 'missing context';
         const context = absentValue;
-        const category = new CategoryDataStub();
         // act
-        const act = () => parseCategory(category, context);
+        const act = () => new TestBuilder()
+          .withContext(context)
+          .parseCategory();
         // assert
         expect(act).to.throw(expectedError);
       });
@@ -72,9 +160,11 @@ describe('CategoryParser', () => {
       const expected = parseDocUrls({ docs: url });
       const category = new CategoryDataStub()
         .withDocs(url);
-      const context = new CategoryCollectionParseContextStub();
       // act
-      const actual = parseCategory(category, context).documentationUrls;
+      const actual = new TestBuilder()
+        .withData(category)
+        .parseCategory()
+        .documentationUrls;
       // assert
       expect(actual).to.deep.equal(expected);
     });
@@ -87,7 +177,11 @@ describe('CategoryParser', () => {
         const category = new CategoryDataStub()
           .withChildren([script]);
         // act
-        const actual = parseCategory(category, context).scripts;
+        const actual = new TestBuilder()
+          .withData(category)
+          .withContext(context)
+          .parseCategory()
+          .scripts;
         // assert
         expect(actual).to.deep.equal(expected);
       });
@@ -102,7 +196,11 @@ describe('CategoryParser', () => {
         const category = new CategoryDataStub()
           .withChildren([script]);
         // act
-        const actual = parseCategory(category, context).scripts;
+        const actual = new TestBuilder()
+          .withData(category)
+          .withContext(context)
+          .parseCategory()
+          .scripts;
         // assert
         expect(actual).to.deep.equal(expected);
       });
@@ -118,7 +216,11 @@ describe('CategoryParser', () => {
           .withCompiler(compiler);
         const expected = scripts.map((script) => parseScript(script, context));
         // act
-        const actual = parseCategory(category, context).scripts;
+        const actual = new TestBuilder()
+          .withData(category)
+          .withContext(context)
+          .parseCategory()
+          .scripts;
         // assert
         expect(actual).to.deep.equal(expected);
       });
@@ -139,7 +241,11 @@ describe('CategoryParser', () => {
               ]),
           ]);
         // act
-        const act = () => parseCategory(category, parseContext).scripts;
+        const act = () => new TestBuilder()
+          .withData(category)
+          .withContext(parseContext)
+          .parseCategory()
+          .scripts;
         // assert
         expect(act).to.not.throw();
       });
@@ -153,9 +259,11 @@ describe('CategoryParser', () => {
       const category = new CategoryDataStub()
         .withName('category name')
         .withChildren(expected);
-      const context = new CategoryCollectionParseContextStub();
       // act
-      const actual = parseCategory(category, context).subCategories;
+      const actual = new TestBuilder()
+        .withData(category)
+        .parseCategory()
+        .subCategories;
       // assert
       expect(actual).to.have.lengthOf(1);
       expect(actual[0].name).to.equal(expected[0].category);
@@ -163,3 +271,30 @@ describe('CategoryParser', () => {
     });
   });
 });
+
+class TestBuilder {
+  private data: CategoryData = new CategoryDataStub();
+
+  private context: ICategoryCollectionParseContext = new CategoryCollectionParseContextStub();
+
+  private factory: CategoryFactoryType = undefined;
+
+  public withData(data: CategoryData) {
+    this.data = data;
+    return this;
+  }
+
+  public withContext(context: ICategoryCollectionParseContext) {
+    this.context = context;
+    return this;
+  }
+
+  public withFactory(factory: CategoryFactoryType) {
+    this.factory = factory;
+    return this;
+  }
+
+  public parseCategory() {
+    return parseCategory(this.data, this.context, this.factory);
+  }
+}
diff --git a/tests/unit/application/Parser/NodeValidation/NodeDataError.spec.ts b/tests/unit/application/Parser/NodeValidation/NodeDataError.spec.ts
new file mode 100644
index 00000000..1b2af9b1
--- /dev/null
+++ b/tests/unit/application/Parser/NodeValidation/NodeDataError.spec.ts
@@ -0,0 +1,67 @@
+import 'mocha';
+import { expect } from 'chai';
+import { INodeDataErrorContext, NodeDataError } from '@/application/Parser/NodeValidation/NodeDataError';
+import { NodeDataErrorContextStub } from '@tests/unit/shared/Stubs/NodeDataErrorContextStub';
+import { NodeType } from '@/application/Parser/NodeValidation/NodeType';
+
+describe('NodeDataError', () => {
+  it('sets message as expected', () => {
+    // arrange
+    const message = 'message';
+    const context = new NodeDataErrorContextStub();
+    const expected = `[${NodeType[context.type]}] ${message}`;
+    // act
+    const sut = new NodeDataErrorBuilder()
+      .withContext(context)
+      .withMessage(expected)
+      .build();
+    // assert
+    expect(sut.message).to.include(expected);
+  });
+  it('sets context as expected', () => {
+    // arrange
+    const expected = new NodeDataErrorContextStub();
+    // act
+    const sut = new NodeDataErrorBuilder()
+      .withContext(expected)
+      .build();
+    // assert
+    expect(sut.context).to.equal(expected);
+  });
+  it('sets stack as expected', () => {
+    // arrange
+    // act
+    const sut = new NodeDataErrorBuilder()
+      .build();
+    // assert
+    expect(sut.stack !== undefined);
+  });
+  it('extends Error', () => {
+    // arrange
+    const expected = Error;
+    // act
+    const sut = new NodeDataErrorBuilder().build();
+    // assert
+    expect(sut).to.be.an.instanceof(expected);
+  });
+});
+
+class NodeDataErrorBuilder {
+  private message = 'error';
+
+  private context: INodeDataErrorContext = new NodeDataErrorContextStub();
+
+  public withContext(context: INodeDataErrorContext) {
+    this.context = context;
+    return this;
+  }
+
+  public withMessage(message: string) {
+    this.message = message;
+    return this;
+  }
+
+  public build(): NodeDataError {
+    return new NodeDataError(this.message, this.context);
+  }
+}
diff --git a/tests/unit/application/Parser/NodeValidation/NodeValidator.spec.ts b/tests/unit/application/Parser/NodeValidation/NodeValidator.spec.ts
new file mode 100644
index 00000000..f76b9032
--- /dev/null
+++ b/tests/unit/application/Parser/NodeValidation/NodeValidator.spec.ts
@@ -0,0 +1,100 @@
+import 'mocha';
+import { expect } from 'chai';
+import { NodeDataError } from '@/application/Parser/NodeValidation/NodeDataError';
+import { NodeValidator } from '@/application/Parser/NodeValidation/NodeValidator';
+import { expectThrowsError } from '@tests/unit/shared/Assertions/ExpectThrowsError';
+import { CategoryDataStub } from '@tests/unit/shared/Stubs/CategoryDataStub';
+import { NodeDataErrorContextStub } from '@tests/unit/shared/Stubs/NodeDataErrorContextStub';
+import { NodeData } from '@/application/Parser/NodeValidation/NodeData';
+import { NodeValidationTestRunner } from './NodeValidatorTestRunner';
+
+describe('NodeValidator', () => {
+  describe('assertValidName', () => {
+    describe('throws if invalid', () => {
+      // arrange
+      const context = new NodeDataErrorContextStub();
+      const sut = new NodeValidator(context);
+      // act
+      const act = (invalidName: string) => sut.assertValidName(invalidName);
+      // assert
+      new NodeValidationTestRunner()
+        .testInvalidNodeName((invalidName) => ({
+          act: () => act(invalidName),
+          expectedContext: context,
+        }));
+    });
+    it('does not throw if valid', () => {
+      // arrange
+      const validName = 'validName';
+      const sut = new NodeValidator(new NodeDataErrorContextStub());
+      // act
+      const act = () => sut.assertValidName(validName);
+      // assert
+      expect(act).to.not.throw();
+    });
+  });
+  describe('assertDefined', () => {
+    describe('throws if missing', () => {
+      // arrange
+      const context = new NodeDataErrorContextStub();
+      const sut = new NodeValidator(context);
+      // act
+      const act = (undefinedNode: NodeData) => sut.assertDefined(undefinedNode);
+      // assert
+      new NodeValidationTestRunner()
+        .testMissingNodeData((invalidName) => ({
+          act: () => act(invalidName),
+          expectedContext: context,
+        }));
+    });
+    it('does not throw if defined', () => {
+      // arrange
+      const definedNode = mockNode();
+      const sut = new NodeValidator(new NodeDataErrorContextStub());
+      // act
+      const act = () => sut.assertDefined(definedNode);
+      // assert
+      expect(act).to.not.throw();
+    });
+  });
+  describe('assert', () => {
+    it('throws expected error if condition is false', () => {
+      // arrange
+      const message = 'error';
+      const falsePredicate = () => false;
+      const context = new NodeDataErrorContextStub();
+      const expected = new NodeDataError(message, context);
+      const sut = new NodeValidator(context);
+      // act
+      const act = () => sut.assert(falsePredicate, message);
+      // assert
+      expectThrowsError(act, expected);
+    });
+    it('does not throw if condition is true', () => {
+      // arrange
+      const truePredicate = () => true;
+      const sut = new NodeValidator(new NodeDataErrorContextStub());
+      // act
+      const act = () => sut.assert(truePredicate, 'ignored error');
+      // assert
+      expect(act).to.not.throw();
+    });
+  });
+  describe('throw', () => {
+    it('throws expected error', () => {
+      // arrange
+      const message = 'error';
+      const context = new NodeDataErrorContextStub();
+      const expected = new NodeDataError(message, context);
+      const sut = new NodeValidator(context);
+      // act
+      const act = () => sut.throw(message);
+      // assert
+      expectThrowsError(act, expected);
+    });
+  });
+});
+
+function mockNode() {
+  return new CategoryDataStub();
+}
diff --git a/tests/unit/application/Parser/NodeValidation/NodeValidatorTestRunner.ts b/tests/unit/application/Parser/NodeValidation/NodeValidatorTestRunner.ts
new file mode 100644
index 00000000..d6f520ac
--- /dev/null
+++ b/tests/unit/application/Parser/NodeValidation/NodeValidatorTestRunner.ts
@@ -0,0 +1,87 @@
+import 'mocha';
+import { NodeDataError, INodeDataErrorContext } from '@/application/Parser/NodeValidation/NodeDataError';
+import { NodeData } from '@/application/Parser/NodeValidation/NodeData';
+import { AbsentObjectTestCases, AbsentStringTestCases, itEachAbsentTestCase } from '@tests/unit/shared/TestCases/AbsentTests';
+import { expectThrowsError } from '@tests/unit/shared/Assertions/ExpectThrowsError';
+
+export interface ITestScenario {
+  readonly act: () => void;
+  readonly expectedContext: INodeDataErrorContext;
+}
+
+export class NodeValidationTestRunner {
+  public testInvalidNodeName(
+    testBuildPredicate: (invalidName: string) => ITestScenario,
+  ) {
+    describe('throws given invalid names', () => {
+      // arrange
+      const testCases = [
+        ...AbsentStringTestCases.map((testCase) => ({
+          testName: `missing name (${testCase.valueName})`,
+          nameValue: testCase.absentValue,
+          expectedMessage: 'missing name',
+        })),
+        {
+          testName: 'invalid type',
+          nameValue: 33,
+          expectedMessage: 'Name (33) is not a string but number.',
+        },
+      ];
+      for (const testCase of testCases) {
+        it(`given "${testCase.testName}"`, () => {
+          const test = testBuildPredicate(testCase.nameValue as never);
+          expectThrowsNodeError(test, testCase.expectedMessage);
+        });
+      }
+    });
+    return this;
+  }
+
+  public testMissingNodeData(
+    testBuildPredicate: (missingNode: NodeData) => ITestScenario,
+  ) {
+    describe('throws given missing node data', () => {
+      itEachAbsentTestCase([
+        ...AbsentObjectTestCases,
+        {
+          valueName: 'empty object',
+          absentValue: {},
+        },
+      ], (absentValue) => {
+        // arrange
+        const expectedError = 'missing node data';
+        // act
+        const test = testBuildPredicate(absentValue as NodeData);
+        // assert
+        expectThrowsNodeError(test, expectedError);
+      });
+    });
+    return this;
+  }
+
+  public runThrowingCase(
+    testCase: {
+      readonly name: string,
+      readonly scenario: ITestScenario,
+      readonly expectedMessage: string
+    },
+  ) {
+    it(testCase.name, () => {
+      expectThrowsNodeError(testCase.scenario, testCase.expectedMessage);
+    });
+    return this;
+  }
+}
+
+export function expectThrowsNodeError(
+  test: ITestScenario,
+  expectedMessage: string,
+) {
+  // arrange
+  const expected = new NodeDataError(expectedMessage, test.expectedContext);
+  // act
+  const act = () => test.act();
+  // assert
+  expectThrowsError(act, expected);
+  return this;
+}
diff --git a/tests/unit/application/Parser/Script/ScriptParser.spec.ts b/tests/unit/application/Parser/Script/ScriptParser.spec.ts
index e94468ec..aa65b557 100644
--- a/tests/unit/application/Parser/Script/ScriptParser.spec.ts
+++ b/tests/unit/application/Parser/Script/ScriptParser.spec.ts
@@ -1,16 +1,21 @@
 import 'mocha';
 import { expect } from 'chai';
-import { parseScript } from '@/application/Parser/Script/ScriptParser';
+import type { ScriptData } from '@/application/collections/';
+import { parseScript, ScriptFactoryType } from '@/application/Parser/Script/ScriptParser';
 import { parseDocUrls } from '@/application/Parser/DocumentationParser';
 import { RecommendationLevel } from '@/domain/RecommendationLevel';
 import { ICategoryCollectionParseContext } from '@/application/Parser/Script/ICategoryCollectionParseContext';
+import { itEachAbsentObjectValue, itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
 import { ScriptCompilerStub } from '@tests/unit/shared/Stubs/ScriptCompilerStub';
 import { ScriptDataStub } from '@tests/unit/shared/Stubs/ScriptDataStub';
 import { EnumParserStub } from '@tests/unit/shared/Stubs/EnumParserStub';
 import { ScriptCodeStub } from '@tests/unit/shared/Stubs/ScriptCodeStub';
 import { CategoryCollectionParseContextStub } from '@tests/unit/shared/Stubs/CategoryCollectionParseContextStub';
 import { LanguageSyntaxStub } from '@tests/unit/shared/Stubs/LanguageSyntaxStub';
-import { itEachAbsentObjectValue, itEachAbsentStringValue } from '@tests/unit/shared/TestCases/AbsentTests';
+import { NodeType } from '@/application/Parser/NodeValidation/NodeType';
+import { expectThrowsNodeError, ITestScenario, NodeValidationTestRunner } from '@tests/unit/application/Parser/NodeValidation/NodeValidatorTestRunner';
+import { Script } from '@/domain/Script';
+import { IEnumParser } from '@/application/Common/Enum';
 
 describe('ScriptParser', () => {
   describe('parseScript', () => {
@@ -19,9 +24,10 @@ describe('ScriptParser', () => {
       const expected = 'test-expected-name';
       const script = ScriptDataStub.createWithCode()
         .withName(expected);
-      const parseContext = new CategoryCollectionParseContextStub();
       // act
-      const actual = parseScript(script, parseContext);
+      const actual = new TestBuilder()
+        .withData(script)
+        .parseScript();
       // assert
       expect(actual.name).to.equal(expected);
     });
@@ -30,86 +36,42 @@ describe('ScriptParser', () => {
       const docs = ['https://expected-doc1.com', 'https://expected-doc2.com'];
       const script = ScriptDataStub.createWithCode()
         .withDocs(docs);
-      const parseContext = new CategoryCollectionParseContextStub();
       const expected = parseDocUrls(script);
       // act
-      const actual = parseScript(script, parseContext);
+      const actual = new TestBuilder()
+        .withData(script)
+        .parseScript();
       // assert
       expect(actual.documentationUrls).to.deep.equal(expected);
     });
-    describe('invalid script', () => {
-      describe('throws when script is absent', () => {
-        itEachAbsentObjectValue((absentValue) => {
-          // arrange
-          const expectedError = 'missing script';
-          const parseContext = new CategoryCollectionParseContextStub();
-          const script = absentValue;
-          // act
-          const act = () => parseScript(script, parseContext);
-          // assert
-          expect(act).to.throw(expectedError);
-        });
-      });
-      it('throws when both function call and code are defined', () => {
-        // arrange
-        const expectedError = 'cannot define both "call" and "code"';
-        const parseContext = new CategoryCollectionParseContextStub();
-        const script = ScriptDataStub
-          .createWithCall()
-          .withCode('code');
-        // act
-        const act = () => parseScript(script, parseContext);
-        // assert
-        expect(act).to.throw(expectedError);
-      });
-      it('throws when both function call and revertCode are defined', () => {
-        // arrange
-        const expectedError = 'cannot define "revertCode" if "call" is defined';
-        const parseContext = new CategoryCollectionParseContextStub();
-        const script = ScriptDataStub
-          .createWithCall()
-          .withRevertCode('revert-code');
-        // act
-        const act = () => parseScript(script, parseContext);
-        // assert
-        expect(act).to.throw(expectedError);
-      });
-      it('throws when neither call or revertCode are defined', () => {
-        // arrange
-        const expectedError = 'must define either "call" or "code"';
-        const parseContext = new CategoryCollectionParseContextStub();
-        const script = ScriptDataStub.createWithoutCallOrCodes();
-        // act
-        const act = () => parseScript(script, parseContext);
-        // assert
-        expect(act).to.throw(expectedError);
-      });
-    });
     describe('level', () => {
       describe('accepts absent level', () => {
         itEachAbsentStringValue((absentValue) => {
           // arrange
-          const parseContext = new CategoryCollectionParseContextStub();
           const script = ScriptDataStub.createWithCode()
             .withRecommend(absentValue);
           // act
-          const actual = parseScript(script, parseContext);
+          const actual = new TestBuilder()
+            .withData(script)
+            .parseScript();
           // assert
           expect(actual.level).to.equal(undefined);
         });
       });
-      describe('parses level as expected', () => {
+      it('parses level as expected', () => {
         // arrange
         const expectedLevel = RecommendationLevel.Standard;
         const expectedName = 'level';
         const levelText = 'standard';
         const script = ScriptDataStub.createWithCode()
           .withRecommend(levelText);
-        const parseContext = new CategoryCollectionParseContextStub();
         const parserMock = new EnumParserStub<RecommendationLevel>()
           .setup(expectedName, levelText, expectedLevel);
         // act
-        const actual = parseScript(script, parseContext, parserMock);
+        const actual = new TestBuilder()
+          .withData(script)
+          .withParser(parserMock)
+          .parseScript();
         // assert
         expect(actual.level).to.equal(expectedLevel);
       });
@@ -121,9 +83,10 @@ describe('ScriptParser', () => {
         const script = ScriptDataStub
           .createWithCode()
           .withCode(expected);
-        const parseContext = new CategoryCollectionParseContextStub();
         // act
-        const parsed = parseScript(script, parseContext);
+        const parsed = new TestBuilder()
+          .withData(script)
+          .parseScript();
         // assert
         const actual = parsed.code.execute;
         expect(actual).to.equal(expected);
@@ -134,9 +97,10 @@ describe('ScriptParser', () => {
         const script = ScriptDataStub
           .createWithCode()
           .withRevertCode(expected);
-        const parseContext = new CategoryCollectionParseContextStub();
         // act
-        const parsed = parseScript(script, parseContext);
+        const parsed = new TestBuilder()
+          .withData(script)
+          .parseScript();
         // assert
         const actual = parsed.code.revert;
         expect(actual).to.equal(expected);
@@ -146,10 +110,11 @@ describe('ScriptParser', () => {
           itEachAbsentObjectValue((absentValue) => {
             // arrange
             const expectedMessage = 'missing context';
-            const script = ScriptDataStub.createWithCode();
             const context: ICategoryCollectionParseContext = absentValue;
             // act
-            const act = () => parseScript(script, context);
+            const act = () => new TestBuilder()
+              .withContext(context)
+              .parseScript();
             // assert
             expect(act).to.throw(expectedMessage);
           });
@@ -163,14 +128,17 @@ describe('ScriptParser', () => {
           const parseContext = new CategoryCollectionParseContextStub()
             .withCompiler(compiler);
           // act
-          const parsed = parseScript(script, parseContext);
+          const parsed = new TestBuilder()
+            .withData(script)
+            .withContext(parseContext)
+            .parseScript();
           // assert
           const actual = parsed.code;
           expect(actual).to.equal(expected);
         });
       });
       describe('syntax', () => {
-        it('set from the context', () => { // test through script validation logic
+        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`;
@@ -180,11 +148,112 @@ describe('ScriptParser', () => {
             .createWithoutCallOrCodes()
             .withCode(duplicatedCode);
           // act
-          const act = () => parseScript(script, parseContext);
+          const act = () => new TestBuilder()
+            .withData(script)
+            .withContext(parseContext);
           // assert
           expect(act).to.not.throw();
         });
       });
     });
+    describe('invalid script data', () => {
+      describe('validates script data', () => {
+        // arrange
+        const createTest = (script: ScriptData): ITestScenario => ({
+          act: () => new TestBuilder()
+            .withData(script)
+            .parseScript(),
+          expectedContext: {
+            type: NodeType.Script,
+            selfNode: script,
+          },
+        });
+        // act and assert
+        new NodeValidationTestRunner()
+          .testInvalidNodeName((invalidName) => {
+            return createTest(
+              ScriptDataStub.createWithCall().withName(invalidName),
+            );
+          })
+          .testMissingNodeData((node) => {
+            return createTest(node as ScriptData);
+          })
+          .runThrowingCase({
+            name: 'throws when both function call and code are defined',
+            scenario: createTest(
+              ScriptDataStub.createWithCall().withCode('code'),
+            ),
+            expectedMessage: 'Cannot define both "call" and "code".',
+          })
+          .runThrowingCase({
+            name: 'throws when both function call and revertCode are defined',
+            scenario: createTest(
+              ScriptDataStub.createWithCall().withRevertCode('revert-code'),
+            ),
+            expectedMessage: 'Cannot define "revertCode" if "call" is defined.',
+          })
+          .runThrowingCase({
+            name: 'throws when neither call or revertCode are defined',
+            scenario: createTest(
+              ScriptDataStub.createWithoutCallOrCodes(),
+            ),
+            expectedMessage: 'Must define either "call" or "code".',
+          });
+      });
+      it(`rethrows exception if ${Script.name} cannot be constructed`, () => {
+        // arrange
+        const expectedError = 'script creation failed';
+        const factoryMock: ScriptFactoryType = () => { throw new Error(expectedError); };
+        const data = ScriptDataStub.createWithCode();
+        // act
+        const act = () => new TestBuilder()
+          .withData(data)
+          .withFactory(factoryMock)
+          .parseScript();
+        // expect
+        expectThrowsNodeError({
+          act,
+          expectedContext: {
+            type: NodeType.Script,
+            selfNode: data,
+          },
+        }, expectedError);
+      });
+    });
   });
 });
+
+class TestBuilder {
+  private data: ScriptData = ScriptDataStub.createWithCode();
+
+  private context: ICategoryCollectionParseContext = new CategoryCollectionParseContextStub();
+
+  private parser: IEnumParser<RecommendationLevel> = new EnumParserStub<RecommendationLevel>()
+    .setupDefaultValue(RecommendationLevel.Standard);
+
+  private factory: ScriptFactoryType = undefined;
+
+  public withData(data: ScriptData) {
+    this.data = data;
+    return this;
+  }
+
+  public withContext(context: ICategoryCollectionParseContext) {
+    this.context = context;
+    return this;
+  }
+
+  public withParser(parser: IEnumParser<RecommendationLevel>) {
+    this.parser = parser;
+    return this;
+  }
+
+  public withFactory(factory: ScriptFactoryType) {
+    this.factory = factory;
+    return this;
+  }
+
+  public parseScript(): Script {
+    return parseScript(this.data, this.context, this.parser, this.factory);
+  }
+}
diff --git a/tests/unit/domain/Script.spec.ts b/tests/unit/domain/Script.spec.ts
index 4ee5850b..6091770a 100644
--- a/tests/unit/domain/Script.spec.ts
+++ b/tests/unit/domain/Script.spec.ts
@@ -24,12 +24,10 @@ describe('Script', () => {
       describe('throws when missing', () => {
         itEachAbsentObjectValue((absentValue) => {
           // arrange
-          const name = 'script-name';
-          const expectedError = `missing code (script: ${name})`;
+          const expectedError = 'missing code';
           const code: IScriptCode = absentValue;
           // act
           const construct = () => new ScriptBuilder()
-            .withName(name)
             .withCode(code)
             .build();
           // assert
diff --git a/tests/unit/shared/Assertions/ExpectThrowsError.ts b/tests/unit/shared/Assertions/ExpectThrowsError.ts
new file mode 100644
index 00000000..62630161
--- /dev/null
+++ b/tests/unit/shared/Assertions/ExpectThrowsError.ts
@@ -0,0 +1,50 @@
+// import * as assert from 'assert';
+import { expect } from 'chai';
+
+// Using manual checks because expect(act).to.throw(obj) does not work
+// chaijs/chai#1065, chaijs/chai#1405
+export function expectThrowsError<T extends Error>(delegate: () => void, expected: T) {
+  // arrange
+  if (!expected) {
+    throw new Error('missing expected');
+  }
+  let actual: T | undefined;
+  // act
+  try {
+    delegate();
+  } catch (error) {
+    actual = error;
+  }
+  // assert
+  expect(Boolean(actual)).to.equal(true, `Expected to throw "${expected.name}" but delegate did not throw at all.`);
+  expect(Boolean(actual?.stack)).to.equal(true, 'Empty stack trace.');
+  expect(expected.message).to.equal(actual.message);
+  expect(expected.name).to.equal(actual.name);
+  expectDeepEqualsIgnoringUndefined(expected, actual);
+}
+
+function expectDeepEqualsIgnoringUndefined(expected: unknown, actual: unknown) {
+  const actualClean = removeUndefinedProperties(actual);
+  const expectedClean = removeUndefinedProperties(expected);
+  expect(expectedClean).to.deep.equal(actualClean);
+}
+
+function removeUndefinedProperties(obj: unknown): unknown {
+  return Object.keys(obj ?? {})
+    .reduce((acc, key) => {
+      const value = obj[key];
+      switch (typeof value) {
+        case 'object': {
+          const cleanValue = removeUndefinedProperties(value); // recurse
+          if (!Object.keys(cleanValue).length) {
+            return { ...acc };
+          }
+          return { ...acc, [key]: cleanValue };
+        }
+        case 'undefined':
+          return { ...acc };
+        default:
+          return { ...acc, [key]: value };
+      }
+    }, {});
+}
diff --git a/tests/unit/shared/Stubs/EnumParserStub.ts b/tests/unit/shared/Stubs/EnumParserStub.ts
index f564466f..320cfe06 100644
--- a/tests/unit/shared/Stubs/EnumParserStub.ts
+++ b/tests/unit/shared/Stubs/EnumParserStub.ts
@@ -23,9 +23,9 @@ export class EnumParserStub<T> implements IEnumParser<T> {
     if (scenario) {
       return scenario.outputValue;
     }
-    if (this.defaultValue) {
+    if (this.defaultValue !== undefined) {
       return this.defaultValue;
     }
-    throw new Error('enum parser is not set up');
+    throw new Error(`Don't know now what to return from ${EnumParserStub.name}, forgot to set-up?`);
   }
 }
diff --git a/tests/unit/shared/Stubs/NodeDataErrorContextStub.ts b/tests/unit/shared/Stubs/NodeDataErrorContextStub.ts
new file mode 100644
index 00000000..2059259b
--- /dev/null
+++ b/tests/unit/shared/Stubs/NodeDataErrorContextStub.ts
@@ -0,0 +1,12 @@
+import { NodeData } from '@/application/Parser/NodeValidation/NodeData';
+import { INodeDataErrorContext } from '@/application/Parser/NodeValidation/NodeDataError';
+import { NodeType } from '@/application/Parser/NodeValidation/NodeType';
+import { CategoryDataStub } from './CategoryDataStub';
+
+export class NodeDataErrorContextStub implements INodeDataErrorContext {
+  public readonly type: NodeType = NodeType.Script;
+
+  public readonly selfNode: NodeData = new CategoryDataStub();
+
+  public readonly parentNode?: NodeData;
+}
diff --git a/tests/unit/shared/TestCases/AbsentTests.ts b/tests/unit/shared/TestCases/AbsentTests.ts
index 5ee0da6f..4d5c611f 100644
--- a/tests/unit/shared/TestCases/AbsentTests.ts
+++ b/tests/unit/shared/TestCases/AbsentTests.ts
@@ -1,16 +1,18 @@
 export function itEachAbsentStringValue(runner: (absentValue: string) => void): void {
-  itEachTestCase(AbsentStringTestCases, runner);
+  itEachAbsentTestCase(AbsentStringTestCases, runner);
 }
 
-export function itEachAbsentObjectValue(runner: (absentValue: AbsentObjectType) => void): void {
-  itEachTestCase(AbsentObjectTestCases, runner);
+export function itEachAbsentObjectValue(
+  runner: (absentValue: AbsentObjectType) => void,
+): void {
+  itEachAbsentTestCase(AbsentObjectTestCases, runner);
 }
 
 export function itEachAbsentCollectionValue<T>(runner: (absentValue: []) => void): void {
-  itEachTestCase(getAbsentCollectionTestCases<T>(), runner);
+  itEachAbsentTestCase(getAbsentCollectionTestCases<T>(), runner);
 }
 
-function itEachTestCase<T>(
+export function itEachAbsentTestCase<T>(
   testCases: readonly IAbsentTestCase<T>[],
   runner: (absentValue: T) => void,
 ): void {
@@ -53,8 +55,8 @@ export function getAbsentCollectionTestCases<T>(): readonly IAbsentCollectionCas
 type AbsentObjectType = undefined | null;
 
 interface IAbsentTestCase<T> {
-  valueName: string;
-  absentValue: T;
+  readonly valueName: string;
+  readonly absentValue: T;
 }
 
 // eslint-disable-next-line @typescript-eslint/no-empty-interface