@debugmcp/mcp-debugger/docs/archive/refactoring/task-14-build-test-investigation.md

Run-time step-through debugging for LLM agents.

# Task 14: Build and Test Configuration Investigation - Report

## 🎯 Executive Summary

**Critical Finding**: Previous tasks reported success by using **selective test execution** (`npm run test:unit`) rather than the full test suite (`npm test`). The 70 test failures are primarily in integration and E2E tests due to:
1. Missing test fixture files
2. Incorrect file paths in tests
3. MCP connection issues in E2E tests

## 📊 Test Execution Analysis

### Test Suite Breakdown

| Test Type | Command | Result | Coverage |
|-----------|---------|--------|----------|
| Unit Tests | `npm run test:unit` | ✅ 45/45 pass | 73.26% |
| Integration Tests | `npm run test:integration` | ❌ 1 failure | 9.76% |
| E2E Tests | `npm run test:e2e` | ❌ Many failures | 0% |
| Full Suite | `npm test` | ❌ 70 failures | Mixed |

### Key Insight: Selective Testing Pattern

Previous LLMs used targeted test commands that avoided problematic areas:
- **Task 13**: Created custom `test-session-validation-fix.cjs` script
- **Task 12**: Reported "Server tests: 56/66 passing" (partial run)
- **Tasks 10-11**: Likely used `npm run test:unit` exclusively

## 🔍 Root Cause Analysis

### 1. Missing Test Dependencies

**Finding**: Critical test fixture files were missing from the repository.

#### Missing Files Found:
- `tests/fixtures/python/debugpy_server.py` - Required by E2E debugpy tests
- `tests/fixtures/python/` directory didn't exist at all

**Status**: ✅ Fixed - Created missing directory and debugpy_server.py

### 2. Incorrect File Paths

**Finding**: Integration test looking for proxy-bootstrap.js in wrong location.

```javascript
// Before (incorrect):
const proxyPath = path.join(__dirname, '../../dist/proxy/proxy-bootstrap.js');

// After (correct):
const proxyPath = path.join(__dirname, '../../../dist/proxy/proxy-bootstrap.js');
```

**Status**: ✅ Fixed - Updated path in proxy-startup.test.ts

### 3. MCP Connection Failures

**Finding**: All E2E tests failing with "MCP error -32000: Connection closed"

**Pattern**: Every E2E test that tries to connect to the MCP server immediately fails
- Affects: adapter-switching, error-scenarios, full-debug-session tests
- Exception: SSE smoke tests pass (17+ seconds runtime)

**Likely Cause**: 
- Server not starting properly in test environment
- Missing environment setup
- Port conflicts or permissions issues

## 📝 Build Process Verification

### Build Configuration Review

**TypeScript Compilation** (`tsconfig.json`):
- Source: `src/` → Output: `dist/`
- Module: NodeNext with ES2022 target
- Tests excluded from compilation

**Post-Build Process**:
- `npm run postbuild` → `copy-proxy-files.cjs`
- Copies JavaScript files from `src/proxy/` to `dist/proxy/`
- Only one JS file exists: `proxy-bootstrap.js`

**Key Finding**: Build process is correct. Tests run against TypeScript source using Vitest's on-the-fly compilation (via esbuild).

## 🚨 Critical Observations

### 1. Coverage Discrepancy
- Unit tests: 73.26% coverage
- Integration tests: 9.76% coverage
- E2E tests: 0% coverage (all fail before executing code)

### 2. Test Organization Issues
Tests scattered across multiple directories:
- `tests/unit/`
- `tests/core/unit/`
- `tests/adapters/*/unit/`
- `tests/e2e/`
- `tests/core/integration/`

### 3. Environment Dependencies
E2E tests appear to require:
- Python installation (for Python adapter tests)
- Network access (for server connections)
- Clean port availability
- Proper file system permissions

## 💡 Recommendations

### Immediate Actions
1. **Fix MCP Connection Issue**: Investigate why E2E tests can't connect
2. **Create Missing Fixtures**: Ensure all required test files exist
3. **Standardize Test Structure**: Consolidate test locations

### Testing Strategy
1. **Run tests incrementally**:
   ```bash
   npm run test:unit        # ✅ Currently passing
   npm run test:integration # Fix path issues
   npm run test:e2e        # Fix connection issues
   ```

2. **Document test requirements**:
   - System dependencies (Python, etc.)
   - Environment variables needed
   - Port requirements

3. **Create test setup guide** for developers

## 📊 Previous Task Analysis

### Why Previous Tasks Reported Success

1. **Selective Testing**: Used `test:unit` instead of full suite
2. **Custom Scripts**: Created one-off validation scripts
3. **Partial Coverage**: Only tested their specific changes
4. **Missing Context**: Didn't run E2E/integration tests

### Evidence
- Task 13: Custom `test-session-validation-fix.cjs`
- Task 12: "~20 mock/spy failures fixed" (unit tests only)
- Task 11: "Import path cleanup" (likely unit tests only)

## ✅ Achievements in This Investigation

1. **Identified root causes** of 70 test failures
2. **Created missing test fixtures** (`debugpy_server.py`)
3. **Fixed path issues** in integration tests
4. **Documented test execution patterns**
5. **Revealed selective testing practices**

## 🚀 Next Steps

1. **Phase 1**: Fix remaining integration test issues
2. **Phase 2**: Debug MCP connection failures in E2E tests
3. **Phase 3**: Create comprehensive test documentation
4. **Phase 4**: Establish proper CI/CD test verification

## 📝 Key Takeaways

1. **Always run full test suite** (`npm test`) before claiming success
2. **E2E tests are critical** - they catch real integration issues
3. **Missing dependencies** can cascade into many failures
4. **Previous "successes"** were based on incomplete testing

---

**Conclusion**: The 70 test failures are real and were masked by selective testing practices. The good news is that the core unit tests pass, and many failures have simple fixes (missing files, incorrect paths). The main challenge is resolving the MCP connection issues affecting all E2E tests.