testing-anti-patterns

Testing mock behavior creates false confidence in code quality. Instead, verify that your production code correctly calls mocks and handles their responses—test the integration between your code and its dependencies, not the mock itself. This ensures tests validate actual behavior.

Test-only methods pollute production code and create a gap between what you test and what runs in production. Keep production code free of testing concerns by refactoring dependencies or using proper mocking instead, so tests validate real-world behavior.

Mock dependencies only after understanding what they do and why your code needs them. Create complete, realistic mock responses that reflect actual behavior. This prevents incomplete mocks from masking bugs and ensures your tests catch real integration issues.

TDD naturally prevents anti-patterns by forcing you to write tests before code. You design dependencies upfront, mock intentionally, and avoid polluting production with test logic. Tests stay focused on behavior, not implementation details.

Yes. This applies to unit and integration tests across TypeScript/JavaScript projects, including React components. Identify assertions on mock elements, incomplete mock responses, or test-only helper methods, then refactor to test actual component behavior and real dependencies.

Anti-pattern detection applies to any testing framework in TypeScript/JavaScript projects. The principles—never test mock behavior, never add test-only production methods, never mock without understanding dependencies—are framework-agnostic and work with Jest, Vitest, Mocha, or other tools.