## Testing Strategy

The project uses a three-tier testing approach:

### Test Categories

1. **Unit Tests** (`apps/api/tests/unit/`)
   - Fast tests with no external dependencies
   - Use SQLite in-memory database
   - Run with: `make test-unit` or `pytest -m unit`

2. **Integration Tests** (`apps/api/tests/integration/`)
   - Test API endpoints with database
   - Use PostgreSQL with transaction rollback
   - Run with: `make test-integration` or `pytest -m integration`

3. **System/E2E Tests** (`e2e/`)
   - End-to-end tests using Playwright
   - Test full user journeys
   - Run with: `make test-e2e`

### Running Tests

```bash
# Run all tests (excludes system tests by default)
make test

# Run specific categories
make test-unit          # Fast unit tests only
make test-integration   # Integration tests with DB
make test-system        # Full stack tests
make test-e2e          # Browser-based E2E tests

# Inside Docker container
docker compose exec api pytest -v -m unit
docker compose exec api pytest -v -m integration
```

### Test Markers

Tests are marked with pytest markers:
- `@pytest.mark.unit` - Fast, isolated tests
- `@pytest.mark.integration` - Tests with database/external services
- `@pytest.mark.system` - Full stack tests

### Shared Fixtures

Common fixtures are in `apps/api/tests/conftest.py`:
- `sqlite_engine` - SQLite engine for unit tests
- `postgres_engine` - PostgreSQL engine for integration tests
- `db_session` - Database session with transaction rollback
- `test_client` - FastAPI TestClient instance