Will Miao 25e6d72c4f test(backend): Phase 1 - Improve testing infrastructure and add error path tests ...

## Changes

### pytest-asyncio Integration
- Add pytest-asyncio>=0.21.0 to requirements-dev.txt
- Update pytest.ini with asyncio_mode=auto and fixture loop scope
- Remove custom pytest_pyfunc_call handler from conftest.py
- Add @pytest.mark.asyncio to 21 async test functions

### Error Path Tests
- Create test_downloader_error_paths.py with 19 new tests covering:
  - DownloadStreamControl state management (6 tests)
  - Downloader configuration and initialization (4 tests)
  - DownloadProgress dataclass validation (1 test)
  - Custom exception handling (2 tests)
  - Authentication header generation (3 tests)
  - Session management (3 tests)

### Documentation
- Update backend-testing-improvement-plan.md with Phase 1 completion status

## Test Results
- All 458 service tests pass
- No regressions introduced

Relates to backend testing improvement plan Phase 1

2026-02-11 10:29:21 +08:00

..

backend-testing-improvement-plan.md

test(backend): Phase 1 - Improve testing infrastructure and add error path tests

2026-02-11 10:29:21 +08:00

coverage_analysis.md

test: add standalone bootstrap and model factory coverage

2025-10-11 22:42:24 +08:00