Response to @KevinHuSh's review question about mocks.
Added:
- Integration tests (10 tests) with real CheckpointService and database
- Documentation explaining unit tests vs integration tests
- Real-world resume scenario test
- Comments in unit tests explaining mock usage
Integration tests cover:
- Actual database operations
- Complete checkpoint lifecycle
- Resume from crash scenario
- Retry logic with real state
- Progress calculation with persistence
Unit tests (mocked) remain for:
- Fast CI/CD feedback (0.04s)
- Interface validation
- No database dependencies
Both test types are valuable and complement each other.