| name | pytest-coverage |
| description | Run pytest with coverage, identify uncovered lines, and iteratively add tests until 100% coverage is reached. |
Goal
Ensure all lines of code in the backend are covered by tests.
Steps
1. Generate Coverage Report
For the entire backend:
cd backend
pytest --cov --cov-report=annotate:cov_annotate
For a specific module:
pytest --cov=app.services.credit_service --cov-report=annotate:cov_annotate
For specific tests:
pytest tests/test_credit_service.py --cov=app.services.credit_service --cov-report=annotate:cov_annotate
2. Read Annotated Output
- Open the
cov_annotate/ directory.
- Each source file has a matching annotated file.
- Lines starting with
! are not covered by tests.
- Files with 100% coverage don't need attention.
3. Add Missing Tests
For each uncovered line:
- Understand what the line does in context.
- Write a focused test that exercises that branch/path.
- For async endpoints, use
pytest-asyncio with async def test_....
- For DB-dependent tests, use isolated fixtures (never the production DB).
4. Iterate Until 100%
Keep running and improving until no ! lines remain:
pytest --cov --cov-report=annotate:cov_annotate
Tips for This Project
- Service-layer tests (e.g.,
test_credit_service.py) should mock external calls (fal_client, S3, etc.).
- Use
pytest.mark.asyncio for async FastAPI endpoints.
- Edge cases to test: invalid input, 0-credit balance, expired sessions, S3 upload failure.
Source: github/awesome-copilot — pytest-coverage
