test(markdownEditorUtils): add unit tests for pure utility functions

[Shubh-Raj]

Closes #603

Add comprehensive unit tests for the pure utility functions in markdownEditorUtils.ts to improve test coverage for the new Markdown Toolbar feature.

Changes

• Add src/tests/utils/markdownEditorUtils.test.ts with 24 unit tests covering:
  • parseLine: 6 tests for whitespace extraction
  • detectPrefix: 9 tests for markdown prefix detection
  • allLinesHavePrefix: 6 tests for prefix validation
  • createLineEditRange: 3 tests for range creation
• Add Monaco editor mock at src/utils/testing/mocks/monaco-editor.ts to enable testing utilities that import Monaco types
• Update vite.config.ts with deps.inline and alias config to use the Monaco mock in tests

Flags

• This PR only tests pure utility functions that don't require Monaco editor mocking beyond types
• The Monaco mock infrastructure added here can be reused for future editor utility tests
• All existing 34 tests continue to pass; total test count increases to 58

Screenshots or Video

N/A - This is a test-only change with no UI modifications.

Related Issues

• Issue feat: Add unit tests for markdownEditorUtils.ts pure utility functions #603

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from Shubh-Raj:shubhraj/tests/markdowneditorutils-unit-tests

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[Copilot]

Pull request overview

Adds Vitest unit coverage for the pure helper functions in src/utils/markdownEditorUtils.ts (used by the Markdown Toolbar feature) and introduces a lightweight monaco-editor mock so these utilities can be imported in tests without pulling in the full Monaco runtime.

Changes:

• Adds 24 unit tests covering createLineEditRange, parseLine, detectPrefix, and allLinesHavePrefix.
• Introduces a monaco-editor module mock for the unit-test environment.
• Updates Vitest config to inline and alias monaco-editor to the mock during tests.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
vite.config.ts	Configures Vitest to alias monaco-editor to a test mock (and inline the dependency).
src/utils/testing/mocks/monaco-editor.ts	Provides a minimal Monaco mock (Selection + basic exports) to support importing editor utilities in unit tests.
src/tests/utils/markdownEditorUtils.test.ts	Adds unit tests for the pure utility functions powering markdown prefix/whitespace logic.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[Copilot]

The Vitest config aliases the entire monaco-editor module to a local mock for all unit tests. This makes it hard to add future tests that rely on real Monaco behavior (or a richer mock) and can cause unrelated test failures when a component imports Monaco at runtime. Consider scoping the Monaco mocking to only the specific test(s) that need it (e.g., vi.mock('monaco-editor', ...) in the test file or in setup.ts with conditional logic), or alternatively remove the runtime Monaco import need by switching the util to import type (so no module-level Monaco load occurs during tests).

Suggested change

	alias: {
	"monaco-editor": fileURLToPath(new URL("./src/utils/testing/__mocks__/monaco-editor.ts", import.meta.url)),
	},

[Copilot]

This mock currently exports only an empty editor object and a Selection class. Because the Vitest config aliases monaco-editor globally, any test that imports code using Monaco runtime APIs (e.g., monaco.languages.*, monaco.editor.*) will throw at runtime with this mock. Either expand the mock to include the minimal runtime shape used by the app (stub languages, editor, etc.), or avoid applying the alias globally and mock Monaco only in the tests that need it.

Suggested change

	export const editor = {};
	/**
	* Minimal stub for the monaco.editor namespace used in tests.
	* Functions are no-ops that return simple disposable-like objects
	* to prevent runtime errors when test code calls Monaco APIs.
	*/
	export const editor = {
	create: (_domElement?: unknown, _options?: unknown) => {
	const model = {
	getValue: (): string => '',
	setValue: (_value: string): void => {
	// no-op
	},
	dispose: (): void => {
	// no-op
	},
	};
	return {
	onDidChangeModelContent: (
	_listener: () => void
	): { dispose: () => void } => ({
	dispose: (): void => {
	// no-op
	},
	}),
	getValue: (): string => '',
	setValue: (_value: string): void => {
	// no-op
	},
	getModel: () => model,
	updateOptions: (_options: unknown): void => {
	// no-op
	},
	dispose: (): void => {
	// no-op
	},
	};
	},
	createModel: (value: string, _language?: string) => ({
	getValue: (): string => value,
	setValue: (_newValue: string): void => {
	// no-op
	},
	dispose: (): void => {
	// no-op
	},
	}),
	setModelLanguage: (_model: unknown, _languageId: string): void => {
	// no-op
	},
	};
	/**
	* Minimal stub for the monaco.languages namespace used in tests.
	*/
	export const languages = {
	register: (_language: unknown): void => {
	// no-op
	},
	setMonarchTokensProvider: (_languageId: string, _tokensProvider: unknown): void => {
	// no-op
	},
	registerCompletionItemProvider: (
	_languageId: string,
	_provider: unknown
	): { dispose: () => void } => ({
	dispose: (): void => {
	// no-op
	},
	}),
	};

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.