python-testing

Define a function decorated with @pytest.fixture that performs setup, yields the resource to the test, then runs teardown code after the yield. Use scope parameters like module or session to control how often the fixture runs.

Use unittest.mock's @patch decorator targeting the import path of the external call, then set return_value or side_effect on the mock. Assert call counts with assert_called_once or assert_awaited_once for async functions.

Yes, pytest-asyncio enables async test support through the @pytest.mark.asyncio decorator. Async fixtures can also be defined with async def and yield to provide resources like async HTTP clients.

Tag tests with custom markers like @pytest.mark.slow, register them in pytest.ini or pyproject.toml, then filter with pytest -m "not slow" or combine expressions like "unit and not slow".

This Skill recommends 80% overall coverage with 100% on critical paths, measured via pytest --cov with term-missing and HTML reports. Coverage below target indicates untested branches that need additional test cases.