Python Testing Patterns

Comprehensive testing strategies for Python applications using pytest, TDD methodology, and best practices.

When to Activate

• Writing new Python code (follow TDD: red, green, refactor)
• Designing test suites for Python projects
• Reviewing Python test coverage
• Setting up testing infrastructure
• Choosing the correct scope (function, module, session) for a pytest fixture
• Debugging flaky tests caused by shared mutable state or incorrect mock namespaces
• Parametrizing tests to cover multiple inputs without duplicating test logic
• Enforcing 80%+ coverage with pytest --cov and understanding which lines are uncovered

Core Testing Philosophy

Test-Driven Development (TDD)