---
title: "Phase 2.7: Comprehensive Testing & Quality Assurance"
labels: ["testing", "quality", "phase-2", "high-priority"]
assignees: []
milestone: "Phase 2 - Intelligence & Usability"
---

## Overview

Establish comprehensive testing infrastructure and quality assurance processes to ensure WizardMerge is reliable, performant, and correct. This includes unit tests, integration tests, performance benchmarks, and fuzzing.

## Related Roadmap Section

Phase 2.7 - Testing & Quality

## Motivation

As WizardMerge grows more complex with semantic merging, SDG analysis, and multi-platform support, we need:
- Confidence that changes don't break existing functionality
- Performance metrics to prevent regressions
- Edge case coverage to handle real-world scenarios
- Quality documentation and examples

## Testing Strategy

### 1. Unit Tests

**Coverage Target**: >90% code coverage

#### Backend (C++)
- [ ] **Three-way merge algorithm**
  - Test all merge cases (clean merge, conflicts, auto-resolution)
  - Test edge cases (empty files, binary files, large files)
  - Test different line endings (LF, CRLF)
  
- [ ] **Semantic mergers**
  - JSON merger tests (objects, arrays, nested structures)
  - YAML merger tests (comments, anchors, multi-document)
  - XML merger tests (namespaces, attributes, DTD)
  - Package file merger tests (version conflicts, dependencies)
  
- [ ] **AST mergers**
  - Python: imports, functions, classes
  - JavaScript: ES6 modules, React components
  - Java: classes, methods, annotations
  - C++: includes, namespaces, templates
  
- [ ] **SDG analysis**
  - Dependency graph construction
  - Edge classification
  - Conflict analysis
  - Suggestion generation
  
- [ ] **Git integration**
  - Git CLI operations
  - Repository detection
  - Branch operations
  - PR/MR fetching

**Framework**: Google Test (gtest)

```cpp
// Example unit test
TEST(ThreeWayMergeTest, NonOverlappingChanges) {
  ThreeWayMerge merger;
  std::string base = "line1\nline2\nline3\n";
  std::string ours = "line1\nline2_modified\nline3\n";
  std::string theirs = "line1\nline2\nline3_modified\n";
  
  auto result = merger.merge(base, ours, theirs);
  
  ASSERT_TRUE(result.success);
  ASSERT_FALSE(result.has_conflicts);
  EXPECT_EQ(result.merged_content, "line1\nline2_modified\nline3_modified\n");
}
```

#### Frontends

**Qt6 (C++)**:
- [ ] UI component tests
- [ ] QML integration tests
- [ ] Model-view tests

**Framework**: Qt Test

**Next.js (TypeScript)**:
- [ ] Component tests (React Testing Library)
- [ ] API client tests
- [ ] Integration tests
- [ ] E2E tests (Playwright or Cypress)

**Framework**: Jest, React Testing Library, Playwright

```typescript
// Example component test
import { render, screen, fireEvent } from '@testing-library/react';
import ConflictPanel from './ConflictPanel';

test('renders conflict and resolves with "ours"', () => {
  const conflict = { id: 1, ours: 'code A', theirs: 'code B' };
  const onResolve = jest.fn();
  
  render(<ConflictPanel conflict={conflict} onResolve={onResolve} />);
  
  const oursButton = screen.getByText('Keep Ours');
  fireEvent.click(oursButton);
  
  expect(onResolve).toHaveBeenCalledWith(1, 'ours');
});
```

### 2. Integration Tests

Test interactions between components:

- [ ] **Backend + Git**
  - Clone repo, create branch, commit changes
  - Fetch PR/MR data, apply merge, create branch
  
- [ ] **Backend + Frontend**
  - API calls from UI
  - WebSocket updates
  - File upload/download
  
- [ ] **End-to-end scenarios**
  - User resolves conflict via UI
  - CLI resolves PR conflicts
  - Batch resolution of multiple files

**Framework**: 
- C++: Integration test suite with real Git repos
- Next.js: Playwright for E2E testing

```typescript
// Example E2E test (Playwright)
test('resolve conflict via web UI', async ({ page }) => {
  await page.goto('http://localhost:3000');
  
  // Upload conflicted file
  await page.setInputFiles('input[type=file]', 'test_conflict.txt');
  
  // Wait for merge analysis
  await page.waitForSelector('.conflict-panel');
  
  // Click "Keep Ours"
  await page.click('button:has-text("Keep Ours")');
  
  // Verify resolution
  const resolved = await page.textContent('.merged-content');
  expect(resolved).toContain('code A');
  expect(resolved).not.toContain('<<<<<<<');
});
```

### 3. Performance Benchmarks

**Goals**:
- Merge time: <100ms for files up to 10MB
- API response: <500ms for typical PRs
- UI rendering: <50ms for typical conflicts
- SDG analysis: <500ms for files up to 2000 lines

**Benchmark Suite**:
```cpp
// Benchmark framework: Google Benchmark
static void BM_ThreeWayMerge_SmallFile(benchmark::State& state) {
  std::string base = generate_file(100);  // 100 lines
  std::string ours = modify_lines(base, 10);
  std::string theirs = modify_lines(base, 10);
  
  ThreeWayMerge merger;
  for (auto _ : state) {
    auto result = merger.merge(base, ours, theirs);
    benchmark::DoNotOptimize(result);
  }
}
BENCHMARK(BM_ThreeWayMerge_SmallFile);

static void BM_ThreeWayMerge_LargeFile(benchmark::State& state) {
  std::string base = generate_file(10000);  // 10k lines
  std::string ours = modify_lines(base, 100);
  std::string theirs = modify_lines(base, 100);
  
  ThreeWayMerge merger;
  for (auto _ : state) {
    auto result = merger.merge(base, ours, theirs);
    benchmark::DoNotOptimize(result);
  }
}
BENCHMARK(BM_ThreeWayMerge_LargeFile);
```

**Metrics to Track**:
- Execution time (median, p95, p99)
- Memory usage
- CPU usage
- Throughput (files/second)

**Regression Detection**:
- Run benchmarks on every commit
- Alert if performance degrades >10%
- Track performance over time

### 4. Fuzzing

Find edge cases and bugs with fuzz testing:

**Targets**:
- [ ] Three-way merge algorithm
- [ ] JSON/YAML/XML parsers
- [ ] Git URL parsing
- [ ] API input validation

**Framework**: libFuzzer, AFL++, or OSS-Fuzz

```cpp
// Example fuzz target
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
  std::string input(reinterpret_cast<const char*>(data), size);
  
  ThreeWayMerge merger;
  try {
    // Try to crash the merger with random input
    auto result = merger.merge(input, input, input);
  } catch (...) {
    // Catch exceptions to continue fuzzing
  }
  
  return 0;
}
```

**Goals**:
- Find crashes and hangs
- Discover edge cases not covered by unit tests
- Improve input validation
- Run continuously in CI

### 5. Test Data & Fixtures

**Real-World Test Cases**:
- [ ] Collect conflicts from popular open-source projects
- [ ] Build test dataset with various conflict types
- [ ] Include edge cases (large files, binary files, unusual encodings)
- [ ] Categorize by difficulty (simple, medium, complex)

**Test Repositories**:
```
tests/
├── fixtures/
│   ├── conflicts/
│   │   ├── simple/
│   │   │   ├── 01-non-overlapping.txt
│   │   │   ├── 02-identical-changes.txt
│   │   │   └── ...
│   │   ├── medium/
│   │   │   ├── 01-json-merge.json
│   │   │   ├── 02-python-imports.py
│   │   │   └── ...
│   │   └── complex/
│   │       ├── 01-sdg-analysis-needed.cpp
│   │       ├── 02-multi-file-dependencies.zip
│   │       └── ...
│   ├── repositories/
│   │   ├── test-repo-1/  # Git repo for integration tests
│   │   ├── test-repo-2/
│   │   └── ...
│   └── api-responses/
│       ├── github-pr-123.json
│       ├── gitlab-mr-456.json
│       └── ...
```

### 6. Continuous Integration

**CI Pipeline**:
```yaml
# .github/workflows/ci.yml
name: CI

on: [push, pull_request]

jobs:
  test-backend:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Build backend
        run: cd backend && ./build.sh
      - name: Run unit tests
        run: cd backend/build && ctest --output-on-failure
      - name: Upload coverage
        uses: codecov/codecov-action@v3
  
  test-frontend-nextjs:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: oven-sh/setup-bun@v1
      - name: Install dependencies
        run: cd frontends/nextjs && bun install
      - name: Run tests
        run: cd frontends/nextjs && bun test
      - name: E2E tests
        run: cd frontends/nextjs && bun run test:e2e
  
  benchmark:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Build backend
        run: cd backend && ./build.sh
      - name: Run benchmarks
        run: cd backend/build && ./benchmarks
      - name: Check for regressions
        run: python scripts/check_benchmark_regression.py
  
  fuzz:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Build fuzzer
        run: cd backend && cmake -DFUZZING=ON . && make
      - name: Run fuzzer (5 minutes)
        run: ./backend/build/fuzzer -max_total_time=300
```

### 7. Code Quality Tools

- [ ] **Static Analysis**: clang-tidy, cppcheck
- [ ] **Code Coverage**: gcov, lcov (C++), Istanbul (JS)
- [ ] **Linting**: cpplint (C++), ESLint (JS), Prettier
- [ ] **Memory Safety**: Valgrind, AddressSanitizer
- [ ] **Security Scanning**: CodeQL (already in use ✅)

```bash
# Run all quality checks
./scripts/quality-check.sh
```

### 8. Documentation & Examples

- [ ] **API Documentation**: Doxygen (C++), JSDoc (JS)
- [ ] **User Guide**: Step-by-step examples
- [ ] **Developer Guide**: Architecture, contributing
- [ ] **Example Conflicts**: Tutorials for common scenarios
- [ ] **Video Demos**: Screen recordings of key features

## Implementation Steps

### Phase 1: Unit Tests (3 weeks)
- [ ] Set up test frameworks
- [ ] Write unit tests for core algorithms
- [ ] Achieve 80% code coverage
- [ ] CI integration

### Phase 2: Integration Tests (2 weeks)
- [ ] Set up test repositories
- [ ] Write integration tests
- [ ] E2E tests for frontends
- [ ] CI integration

### Phase 3: Performance Benchmarks (1 week)
- [ ] Set up benchmark framework
- [ ] Write benchmark suite
- [ ] Baseline measurements
- [ ] Regression detection

### Phase 4: Fuzzing (1 week)
- [ ] Set up fuzzing infrastructure
- [ ] Write fuzz targets
- [ ] Run continuous fuzzing
- [ ] Fix discovered issues

### Phase 5: Quality Tools (1 week)
- [ ] Integrate static analysis
- [ ] Set up code coverage
- [ ] Memory safety checks
- [ ] CI integration

### Phase 6: Documentation (2 weeks)
- [ ] Generate API docs
- [ ] Write user guide
- [ ] Create examples
- [ ] Video demos

## Acceptance Criteria

- [ ] >90% code coverage for backend
- [ ] >80% code coverage for frontends
- [ ] All unit tests pass
- [ ] All integration tests pass
- [ ] Performance benchmarks meet targets
- [ ] Zero crashes from fuzzing (after fixes)
- [ ] Documentation complete and accurate
- [ ] CI pipeline green on all commits

## Priority

**HIGH** - Quality and reliability are essential for user trust

## Estimated Effort

10 weeks (can be done in parallel with feature development)

## Dependencies

- Core features implemented (Phase 1 and 2)

## Related Issues

- #TBD (Phase 2 completion)
- #TBD (All feature implementation issues)

## Success Metrics

- 0 critical bugs in production
- <1% test failure rate
- 95% user satisfaction with stability
- Performance targets met consistently

## Test Coverage Goals

| Component | Coverage Target |
|-----------|-----------------|
| Three-way merge | 95% |
| Semantic mergers | 90% |
| AST mergers | 90% |
| SDG analysis | 85% |
| Git integration | 90% |
| API endpoints | 95% |
| UI components | 80% |
| Overall | 90% |
