@debugmcp/mcp-debugger/docs/archive/refactoring/task-4.4-mock-adapter-language-fix-summary.md

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# Task 4.4: Mock Adapter Language Registration Fix - Summary

## 🎯 Objective
Fix the language registration for the mock adapter to ensure it uses `'mock'` as its language identifier, not `'javascript'`. This prevents conflicts with future language adapters and clarifies that the mock adapter is for testing purposes only.

## ✅ What Was Fixed

### 1. **Server Language Metadata** (`src/server.ts`)
Changed the hardcoded case in `getLanguageMetadata()`:
```typescript
// Before:
case 'javascript':
  return {
    id: 'javascript',
    displayName: 'JavaScript (Mock)',
    ...
  };

// After:
case 'mock':
  return {
    id: 'mock',
    displayName: 'Mock',
    ...
  };
```

### 2. **Server Test Mock** (`tests/core/unit/server/server.test.ts`)
Updated the mock to return correct supported languages:
```typescript
// Before:
getSupportedLanguages: vi.fn().mockReturnValue(['python', 'javascript']),

// After:
getSupportedLanguages: vi.fn().mockReturnValue(['python', 'mock']),
```

### 3. **Session Store Test** (`tests/core/unit/session/session-store.test.ts`)
Updated error handling test to use a clearly invalid language:
```typescript
// Before:
language: 'javascript' as DebugLanguage

// After:
language: 'unsupported' as DebugLanguage
```

## ✅ What Was Already Correct

1. **DebugLanguage Enum** (`src/session/models.ts`)
   - Already had `MOCK = 'mock'` defined

2. **Mock Adapter Registration** (`src/container/dependencies.ts`)
   - Already registered with `DebugLanguage.MOCK`

3. **Mock Adapter Implementation** (`src/adapters/mock/mock-debug-adapter.ts`)
   - Already reported `readonly language = DebugLanguage.MOCK`

## 🔍 Verification Results

Running `list_supported_languages` now correctly returns:
```json
{
  "languages": [
    {
      "id": "python",
      "displayName": "Python",
      "version": "1.0.0",
      "requiresExecutable": true,
      "defaultExecutable": "python"
    },
    {
      "id": "mock",
      "displayName": "Mock",
      "version": "1.0.0",
      "requiresExecutable": false
    }
  ]
}
```

## 🚫 Impact on Future JavaScript Support

- No references to `'javascript'` remain in the codebase related to the mock adapter
- A real JavaScript adapter can be implemented without conflicts
- Clear separation between test infrastructure (mock) and real language adapters

## 📊 Test Results

The changes have been verified to:
1. ✅ Correctly report supported languages as `['python', 'mock']`
2. ✅ Allow creation of sessions with language `'mock'`
3. ✅ Reject creation of sessions with language `'javascript'` (as expected)
4. ✅ Maintain all existing test functionality

## 🔧 Technical Details

### Files Modified:
1. `src/server.ts` - Updated language metadata switch case
2. `tests/core/unit/server/server.test.ts` - Fixed mock setup
3. `tests/core/unit/session/session-store.test.ts` - Updated test for clarity

### No Breaking Changes:
- Existing Python functionality unchanged
- Mock adapter continues to work for all tests
- No API changes for consumers

## 📝 Notes

- The session store test was using `'javascript'` to test error handling for unsupported languages. This was changed to `'unsupported'` to make the test's intent clearer.
- The test file import paths in `server.test.ts` were also corrected from relative paths like `../../src/` to `../../../../src/` to match the new test structure.

## ✅ Task Complete

The mock adapter is now properly registered and identified as `'mock'` throughout the codebase, preventing any conflicts with future JavaScript adapter implementations.