python-tests.md

Python test guidelines

• Always add type hints including the return value.
  • The type of the mocker fixture is MockerFixture. It is imported as from pytest_mock import MockerFixture.
• All test function names must start with test_.
• Test files must be named test_*.py.
• Use @pytest.mark.parametrize for parametrised tests.
• Use @pytest.mark.asyncio for asynchronous tests.
• Use pytest.raises for testing exceptions.
• Use @pytest.fixture for fixtures.
• Do not create new fixtures inside test files.
• All fixtures must be defined in the tests/conftest.py file.
• Do not add docstrings to test functions or methods.
• Mock external dependencies and IO operations in tests.
• Prefer exercising the package under test through its public APIs. Do not import names beginning with _ from that package, and do not mocker.patch those names, except when patching a third-party native binding that upstream exposes under a leading underscore (as many C extensions do).
• If a parameter must exist in a callback, use _ as the identifier if it is not a keyword argument.
• Use the runner fixture (type CliRunner) from conftest.py for testing Click commands.
• Test Click commands by checking result.exit_code and result.output.
• Use mocker.patch for complex mock setups; monkeypatch.setattr for simple attribute replacement.