## 14. Testing Strategy

**Recommendation**: Comprehensive testing pyramid.

### Testing Layers

1. **Unit Tests** (70% coverage target):
   - Business logic functions (100% coverage)
   - Matching algorithms (95% coverage, focus on edge cases)
   - Economic calculations (100% coverage, ±€0.01 accuracy)
   - Data validation (100% coverage, all error paths)

2. **Integration Tests** (20% of test suite):
   - API endpoints (200+ test cases, all CRUD operations)
   - Database operations (Neo4j + PostgreSQL integration)
   - Event processing (Watermill pubsub reliability)
   - Service integrations (external APIs, IoT devices)

3. **E2E Tests** (10% of test suite):
   - Critical user flows (match discovery → connection → implementation)
   - Match discovery and connection flow (85% success rate target)
   - Payment processing (Stripe integration, transaction success rate >99.5%)
   - Cross-browser compatibility (Chrome, Firefox, Safari, Edge)

### Testing Tools

- **Backend**: 
  - Built-in `testing` package (Go 1.25 improvements)
  - `github.com/stretchr/testify`: Assertions, suites, mocks
  - `github.com/golang/mock` or `github.com/vektra/mockery/v2`: Mocking
- **API Testing**: 
  - `net/http/httptest`: Built-in HTTP testing
  - `github.com/go-resty/resty/v2`: For integration tests
- **E2E**: Playwright or Cypress
- **Graph Database Testing**: 
  - Testcontainers: `github.com/testcontainers/testcontainers-go`
  - Neo4j test container setup
- **Load Testing**: 
  - `k6` (Go-based, recommended)
  - `github.com/tsenart/vegeta`: HTTP load testing library
- **Benchmarking**: Built-in `go test -bench`

### Test Data Strategy

- **Fixtures**: Realistic test data generators
- **Test Database**: Isolated test environment
- **Snapshots**: Graph database snapshots for integration tests
- **Mocking**: External APIs (government registries, payment providers)

---