pythonista-testing

To start TDD with Python tests, write a failing test before the implementation code. This skill enforces TDD workflows by providing reference patterns and checklists to guide bug fixes and new features through structured test-first cycles.

Pytest fixtures and mocking best practices involve keeping test data clean and using pure functions. This skill provides clear mocking rules and fixture patterns to ensure robust test design and maintainable invariant checks across Python projects.

Python tests may pass without catching bugs if they lack proper invariant checks. This skill helps avoid sham tests by promoting invariant-based testing, ensuring tests actually verify expected behaviors rather than just executing code paths.

Yes, this approach applies to end-to-end testing in Python. The skill provides robust patterns for end-to-end testing alongside unit tests, enforcing consistent mocking rules and fixture management to maintain reliability across the full testing spectrum.

The best way to check test coverage is running the suite with pytest --cov. This skill supports reviewing and maintaining tests by enforcing best practices and using coverage verification to ensure tests meet invariant-based reliability standards.

Prior knowledge of invariants helps but is not strictly required. This skill guides teams to adopt invariant-based testing through reference patterns and checklists, making it accessible for improving test reliability and maintainability.