Pytest

Clean up pytest test signatures using @pytest.mark.usefixtures to inject implicit fixtures without autouse or unused parameter warnings.

Write readable parametrized tests with pytest.param for better test names, conditional skips, custom IDs, and structured test data.

Mock pydantic_settings in pytest tests by patching the settings class to prevent flaky tests from environment variable dependencies.

Combine session and function-scoped pytest fixtures to avoid expensive test setup while maintaining test isolation and preventing state coupling.

Master Python mocking: patch objects at their import location, not where they're defined, to avoid common unittest.mock pitfalls.

Mock chained datetime methods in Python tests using unittest.mock to handle immutable datetime objects without external dependencies.

Create dynamic pytest fixtures with @pytest.fixture(params) to run tests with multiple configurations and parameter combinations.

Combine pytest fixtures with unittest.mock.patch for clean, reusable test mocking patterns that integrate seamlessly with pytest's ecosystem.