@debugmcp/mcp-debugger/docs/archive/refactoring/task-9-test-failure-analysis.md

Run-time step-through debugging for LLM agents.

# Test Failure Analysis Report

## Executive Summary
- Total failures: 67 (4 pre-existing, 63 new)
- Major categories: 5 distinct failure patterns
- Critical blockers: MCP Connection errors affecting all E2E tests
- **Task 8 Impact**: Catastrophic regression - increased failures from 4 to 67

## Pre-Task 8 Baseline
### Failed Tests (Count: 4)
Based on analysis of pre-task8-results.txt:
1. `tests/e2e/container-path-translation.test.ts` - Path display issue on Windows
   - Error: Expected relative path but got absolute Windows path

### Test Suite Stats Before Task 8:
- Total tests: 57
- Failed: 4 (7% failure rate)
- Coverage: 89.83% statements

## Current State Analysis (After Task 8)
### Test Suite Stats:
- Total tests: 63
- Failed: 67 (>100% - some test files failing entirely)
- Coverage: 75.19% statements (14.64% drop!)

## Failure Categories

### Category 1: MCP Connection/Protocol Issues (25+ tests)
#### Symptoms:
- "MCP error -32000: Connection closed" in all E2E tests
- Affects entire E2E test suite
#### Root Cause:
- Likely related to new adapter registry or session validation changes
- MCP server may be crashing on startup or failing to initialize
#### Affected Tests:
- `tests/e2e/adapter-switching.test.ts` (2 failures)
- `tests/e2e/error-scenarios.test.ts` (11 failures)
- `tests/e2e/full-debug-session.test.ts` (3 failures)
- `tests/e2e/mcp-server-smoke.test.ts` (2 failures)
#### Fix Complexity: **Critical/Complex**

### Category 2: Import/Module Resolution Errors (15+ tests)
#### Symptoms:
- "Cannot find module" errors
- Tests can't locate moved files after reorganization
#### Root Cause:
- Test reorganization from Task 4 not properly updated
- Import paths still pointing to old locations
#### Affected Tests:
- `tests/core/integration/container-paths.test.ts`
- `tests/core/unit/utils/logger.test.ts`
- `tests/core/unit/utils/path-translator.test.ts`
- Multiple unit tests failing to import source modules
#### Fix Complexity: **Simple** - Update import paths

### Category 3: Mock/Spy Configuration Issues (20+ tests)
#### Symptoms:
- Spies not being called when expected
- Mock setup failing or not matching new code structure
#### Root Cause:
- Task 8's changes to server.ts and session management broke mock expectations
- New adapter registry pattern not properly mocked
#### Affected Tests:
- `tests/core/unit/server/server.test.ts` (12 failures)
- `tests/core/unit/session/session-manager-*.test.ts` (multiple)
- `tests/core/unit/adapters/adapter-registry.test.ts` (7 failures)
#### Fix Complexity: **Medium** - Update mocks to match new architecture

### Category 4: Session State Management Issues (5+ tests)
#### Symptoms:
- Session lifecycle state not properly tracked
- Language validation failing
#### Root Cause:
- Task 8's new SessionLifecycleState not integrated with tests
- Session store behavior changed
#### Affected Tests:
- `tests/core/unit/session/session-store.test.ts` (1 failure - language validation)
- `tests/core/unit/session/session-manager-edge-cases.test.ts` (1 failure)
#### Fix Complexity: **Medium** - Update tests for new state model

### Category 5: Build/Compilation Issues (2 tests)
#### Symptoms:
- TypeScript module resolution failures
- Build artifacts not found
#### Root Cause:
- File reorganization incomplete
- Build configuration may need updates
#### Affected Tests:
- Various import failures across test suite
#### Fix Complexity: **Simple** - Fix build configuration

## Task 8 Impact Analysis

### Tests Broken by Task 8:
1. **All E2E tests** - MCP connection failures (was working before)
2. **Server unit tests** - Mock expectations broken by new validation logic
3. **Session manager tests** - New state model not compatible
4. **Adapter registry tests** - New component not properly tested
5. **Import paths** - Reorganization side effects

### Tests That Remained Broken:
1. Container path translation (Windows path issue) - pre-existing

### New Issues Introduced:
1. **Adapter Registry**: New component lacks proper test integration
2. **Session Validation**: Error propagation not working as intended
3. **MCP Server Startup**: Completely broken in test environment
4. **Coverage Drop**: 14.64% decrease indicates significant untested code

## Root Cause Summary

Task 8 attempted to fix session validation but:
1. **Broke MCP server initialization** in test environment
2. **Introduced untested adapter registry** that fails to initialize
3. **Changed session state model** without updating tests
4. **Modified error handling** in ways that break existing mocks

## Prioritized Fix Plan

### 1. **Critical** - MCP Connection Errors
- Blocks all E2E testing
- Investigate server initialization with new adapter registry
- May need to temporarily disable adapter registry in tests

### 2. **High** - Import Path Errors  
- Quick wins that unblock many tests
- Run import fix scripts or manually update paths
- Estimated effort: 2-3 hours

### 3. **High** - Mock/Spy Updates
- Update mocks to match new server/session architecture
- Focus on server.test.ts first as it has most failures
- Estimated effort: 4-6 hours

### 4. **Medium** - Session State Model
- Update tests to use new SessionLifecycleState
- Ensure backward compatibility works
- Estimated effort: 2-3 hours

### 5. **Low** - Remaining Issues
- Windows path display formatting
- Minor test adjustments

## Recommended Next Tasks

### Task 10: Emergency Fix - Restore E2E Test Functionality
- Focus: Fix MCP connection errors blocking all E2E tests
- Approach: Debug server initialization, potentially rollback adapter registry
- Success metric: E2E tests can connect to MCP server

### Task 11: Import Path Cleanup
- Focus: Fix all module resolution errors
- Approach: Systematic update of import paths
- Success metric: No "Cannot find module" errors

### Task 12: Mock Infrastructure Update
- Focus: Update test mocks for new architecture
- Approach: Rewrite mocks to match Task 8 changes
- Success metric: Unit tests pass with proper mocks

### Task 13: Session State Test Migration
- Focus: Update tests for new session state model
- Approach: Migrate to SessionLifecycleState enums
- Success metric: Session tests accurately test new model

## Regression Prevention Notes

### Why Task 8 Broke Everything:
1. **No incremental testing**: Changes were too broad without testing each step
2. **Architectural changes**: Adding adapter registry changed initialization flow
3. **Mock brittleness**: Tests too tightly coupled to implementation
4. **Missing integration tests**: No tests for adapter registry integration

### Prevention Strategies:
1. **Test each change**: Run tests after each file modification
2. **Integration tests first**: When adding new components, test integration
3. **Gradual refactoring**: Break large changes into smaller PRs
4. **Mock flexibility**: Use partial mocks and focus on behavior, not implementation

## Conclusion

Task 8's attempt to fix session validation has created a testing crisis. The changes introduced:
- A new adapter registry that breaks server initialization
- Session state changes that invalidate existing tests  
- Import path confusion from earlier reorganization
- Mock expectations that no longer match reality

The priority must be restoring basic E2E test functionality before addressing the original session validation issue. This will require either fixing or temporarily reverting the adapter registry changes.