Refactor to enforce strictNullChecks

This commit applies `strictNullChecks` to the entire codebase to improve
maintainability and type safety. Key changes include:

- Remove some explicit null-checks where unnecessary.
- Add necessary null-checks.
- Refactor static factory functions for a more functional approach.
- Improve some test names and contexts for better debugging.
- Add unit tests for any additional logic introduced.
- Refactor `createPositionFromRegexFullMatch` to its own function as the
  logic is reused.
- Prefer `find` prefix on functions that may return `undefined` and
  `get` prefix for those that always return a value.

tests/unit/presentation/components/Code/CodeButtons/Save/Instructions/CodeInstruction.spec.ts

@@ -6,6 +6,7 @@ import { InjectionKeys } from '@/presentation/injectionSymbols';
 import { Clipboard } from '@/presentation/components/Shared/Hooks/Clipboard/Clipboard';
 import { UseClipboardStub } from '@tests/unit/shared/Stubs/UseClipboardStub';
 import { ClipboardStub } from '@tests/unit/shared/Stubs/ClipboardStub';
+import { expectExists } from '@tests/shared/Assertions/ExpectExists';
 
 const DOM_SELECTOR_CODE_SLOT = 'code';
 const DOM_SELECTOR_COPY_BUTTON = '.copy-button';
@@ -40,7 +41,7 @@ describe('CodeInstruction.vue', () => {
       const calls = clipboardStub.callHistory;
       expect(calls).to.have.lengthOf(1);
       const call = calls.find((c) => c.methodName === 'copyText');
-      expect(call).toBeDefined();
+      expectExists(call);
       const [actualCode] = call.args;
       expect(actualCode).to.equal(expectedCode);
     });

tests/unit/presentation/components/Code/CodeButtons/Save/Instructions/Data/InstructionsBuilder.spec.ts

@@ -1,22 +1,18 @@
 import { describe, it, expect } from 'vitest';
 import { OperatingSystem } from '@/domain/OperatingSystem';
 import { IInstructionsBuilderData, InstructionsBuilder, InstructionStepBuilderType } from '@/presentation/components/Code/CodeButtons/Save/Instructions/Data/InstructionsBuilder';
-import { itEachAbsentObjectValue } from '@tests/unit/shared/TestCases/AbsentTests';
 import { IInstructionInfo, IInstructionListStep } from '@/presentation/components/Code/CodeButtons/Save/Instructions/InstructionListData';
 
 describe('InstructionsBuilder', () => {
   describe('withStep', () => {
-    describe('throws when step is missing', () => {
-      itEachAbsentObjectValue((absentValue) => {
-        // arrange
-        const expectedError = 'missing stepBuilder';
-        const data = absentValue;
-        const sut = new InstructionsBuilder(OperatingSystem.Linux);
-        // act
-        const act = () => sut.withStep(data);
-        // assert
-        expect(act).to.throw(expectedError);
-      });
+    it('returns itself', () => {
+      // arrange
+      const expected = new InstructionsBuilder(OperatingSystem.Android);
+      const step = () => createMockStep();
+      // act
+      const actual = expected.withStep(step);
+      // assert
+      expect(actual).to.equal(expected);
     });
   });
   describe('build', () => {
@@ -66,18 +62,6 @@ describe('InstructionsBuilder', () => {
       expect(true);
       expect(actual).to.equal(expected);
     });
-    describe('throws when data is missing', () => {
-      itEachAbsentObjectValue((absentValue) => {
-        // arrange
-        const expectedError = 'missing data';
-        const data = absentValue;
-        const sut = new InstructionsBuilder(OperatingSystem.Linux);
-        // act
-        const act = () => sut.build(data);
-        // assert
-        expect(act).to.throw(expectedError);
-      });
-    });
   });
 });
 

tests/unit/presentation/components/Code/CodeButtons/Save/Instructions/InstructionListDataFactory.spec.ts

@@ -1,31 +1,11 @@
 import { describe, it, expect } from 'vitest';
 import { OperatingSystem } from '@/domain/OperatingSystem';
-import { getInstructions, hasInstructions } from '@/presentation/components/Code/CodeButtons/Save/Instructions/InstructionListDataFactory';
+import { getInstructions } from '@/presentation/components/Code/CodeButtons/Save/Instructions/InstructionListDataFactory';
 import { getEnumValues } from '@/application/Common/Enum';
 import { InstructionsBuilder } from '@/presentation/components/Code/CodeButtons/Save/Instructions/Data/InstructionsBuilder';
 
 describe('InstructionListDataFactory', () => {
-  const supportedOsList = [OperatingSystem.macOS];
-  describe('hasInstructions', () => {
-    it('return true if OS is supported', () => {
-      // arrange
-      const expected = true;
-      // act
-      const actualResults = supportedOsList.map((os) => hasInstructions(os));
-      // assert
-      expect(actualResults.every((result) => result === expected));
-    });
-    it('return false if OS is not supported', () => {
-      // arrange
-      const expected = false;
-      const unsupportedOses = getEnumValues(OperatingSystem)
-        .filter((value) => !supportedOsList.includes(value));
-      // act
-      const actualResults = unsupportedOses.map((os) => hasInstructions(os));
-      // assert
-      expect(actualResults.every((result) => result === expected));
-    });
-  });
+  const supportedOsList = [OperatingSystem.macOS, OperatingSystem.Linux];
   describe('getInstructions', () => {
     it('returns expected if os is supported', () => {
       // arrange
@@ -35,5 +15,16 @@ describe('InstructionListDataFactory', () => {
       // assert
       expect(actualResults.every((result) => result instanceof InstructionsBuilder));
     });
+    it('return undefined if OS is not supported', () => {
+      // arrange
+      const expected = undefined;
+      const fileName = 'test.file';
+      const unsupportedOses = getEnumValues(OperatingSystem)
+        .filter((value) => !supportedOsList.includes(value));
+      // act
+      const actualResults = unsupportedOses.map((os) => getInstructions(os, fileName));
+      // assert
+      expect(actualResults.every((result) => result === expected));
+    });
   });
 });