testing-anti-patterns

Testing mock behavior instead of actual system behavior happens when assertions verify mock interactions rather than real component outputs. You must enforce TDD principles to ensure tests validate actual application behavior and maintain code integrity.

Adding test-only methods to production code pollutes classes and breaks code integrity. You should prevent this anti-pattern by designing testable production code through dependency injection rather than exposing test-specific internal methods.

Mocks break during refactoring when dependencies are mocked without understanding them. Informed mocking requires understanding dependency contracts before mocking to prevent tests from failing due to incorrect mock configurations.

The best way to write tests for new features is to verify your application correctly handles realistic data instead of just checking that a mock API client returns specific JSON. This ensures tests validate actual system behavior.

Integration tests should not be treated as an afterthought. Enforcing TDD principles ensures integration tests are planned during development to verify actual system behavior rather than being retrofitted later.