[Feature] Add unit tests for revertOpenModule command

Summary

The revertOpenModule.ts command implements functionality to revert extension modifications to the open/opn package module, but currently lacks unit test coverage.

Motivation

• Test coverage gap: src/extension/commands/revertOpenModule.ts (127 lines) has no test file
• Complex logic: File system operations, version checks, and pnpm support require testing
• Error-prone operations: File deletion and JSON modification need validation
• Maintenance: Tests would prevent regressions in complex conditional logic

Current State

• Source file: src/extension/commands/revertOpenModule.ts (127 lines)
• Test file: Does not exist
• Complexity: Package manager detection, version comparison, file operations

Command Functionality

The revertOpenModule command:

• Detects React Native version to determine package name ("open" vs "opn")
• Supports both npm and pnpm package managers
• Deletes open-main.js file from node_modules
• Modifies package.json to remove custom entry point
• Handles multiple error cases with localized messages

Proposed Changes

Create test/extension/commands/revertOpenModule.test.ts with coverage for:

1. Version detection:

   • Test RN >= 0.60.0 uses "open" package
   • Test RN < 0.60.0 uses "opn" package
   • Test canary version handling

2. Package manager support:

   • Test npm project path resolution
   • Test pnpm project path resolution (.pnpm folder detection)
   • Test open module discovery in pnpm structure

3. File operations:

   • Mock fs operations (existsSync, unlinkSync, writeFileSync)
   • Test open-main.js deletion
   • Test package.json main entry deletion
   • Test error handling for missing files

4. Error cases:

   • Module not found
   • File deletion failures
   • package.json modification failures

Test Structure Example

describe('RevertOpenModule', () => {
  let command: RevertOpenModule;
  let mockProject: AppLauncher;
  let fsMock: sinon.SinonStubbedInstance<typeof fs>;

  describe('version detection', () => {
    it('should use "open" for RN >= 0.60.0', async () => { /* ... */ });
    it('should use "opn" for RN < 0.60.0', async () => { /* ... */ });
  });

  describe('pnpm support', () => {
    it('should detect pnpm project', async () => { /* ... */ });
    it('should resolve open module in .pnpm folder', async () => { /* ... */ });
  });

  describe('file operations', () => {
    it('should delete open-main.js', async () => { /* ... */ });
    it('should update package.json main entry', async () => { /* ... */ });
    it('should handle missing files gracefully', async () => { /* ... */ });
  });
});

Benefits

• Validate complex file system operations
• Ensure pnpm support works correctly
• Catch version detection regressions
• Improve error handling reliability
• Document expected behavior through tests

References

• Source: src/extension/commands/revertOpenModule.ts
• Related: SettingsHelper.getPackageManager(), ProjectVersionHelper
• Similar patterns: File operation tests in other command tests

Start with src/extension/commands/revertOpenModule.ts and compare similar command tests, then inspect SettingsHelper.getPackageManager() and ProjectVersionHelper. Create test/extension/commands/revertOpenModule.test.ts covering React Native version detection, npm and pnpm resolution, file operations, and the listed error cases. Done means the command's conditional paths and failures are covered by passing unit tests.