python-tests

# Python Test Style - Pytest is used to run tests. - Do not add `@pytest.mark.asyncio` to any test. Async tests are automatically detected and run by the async runner; the decorator is unnecessary clutter. - Do not add a `-> None` return type annotation to test functions. This is not a common convention in pytest and adds unnecessary verbosity. - When mocking a class, do not define a new class. Use `unittest.mock.MagicMock` or `unittest.mock.AsyncMock`, with the `spec` constructor argument when necessary. - The name of the mocked class should be prefixed with `mock`, not `fake`. - Prefer pytest fixtures over helper methods. - Do not repeat fixtures, if a fixture is needed in multiple test files, place it in a `conftest.py` file. - When creating a fixture follow this pattern: ```python @pytest.fixture(name="<fixture_name>"[, scope="<scope>"]) def <fixture_name>_fixture() -> <return_type>: ... ``` Only specify the scope argument when the value is something other than "function". - Prefer `pytest.mark.parametrize` over creating individual tests for different input types. - If a fixture is needed for a test, but either does not return a value or the value is not used in the test, use the `@pytest.mark.usefixtures` decorator. - `tests/conftest.py` contains a `restore_environ_fixture` fixture that restores the environment variables to their original state after each test, it is defined with `autouse=True` so it is automatically applied to all tests. If you need to modify the environment variables in a test, do so using `os.environ` and the fixture will restore them after the test completes. There is no need to use `monkeypatch.setenv` to modify environment variables in tests. - Avoid defensive programming in tests. If a test fails, it should fail loudly and clearly, rather than silently passing due to defensive checks. For example ```python data = results["data"] ``` is preferred over ```python data = results.get("data") ``` Simply allow the resulting KeyError to be raised if the "data" key is not present in the results dictionary, as this will provide a clear indication of what went wrong in the test. ## Common Commands ```bash # Focused test loop uv run pytest -k "<pattern>" # Run all tests uv run pytest ``` ## Do Not Write Tests For - Documentation. - Test helper code under `tests/_utils/`. - Package metadata or wheel installation behavior. ## References - `pyproject.toml` - `tests/conftest.py`