testing-anti-patterns

Testing mocks instead of actual behavior happens when assertions check mock internal state rather than real functionality. Focus assertions on the component's actual output and side effects, not whether the mock was called or how it was configured. Verify real behavior by testing the actual dependency interactions.

Test-only production methods bloat your codebase and create maintenance confusion between test and production concerns. Keep production classes focused on their actual business logic. Instead, refactor code to be naturally testable or use dependency injection to control behavior during testing.

Safe mocking starts by understanding what the dependency does and why you're replacing it—don't mock without clarity on its behavior and contracts. Complete mocks that capture the full interface reduce mysterious test failures. Verify your mocks match real dependency behavior to catch integration issues early.

Tests gain confidence by verifying actual component behavior against real dependencies, not mock implementations. Avoid assertions on mock state; test observable outputs and side effects instead. Use gate-based testing—check preconditions, execute the action, verify results—to ensure tests reflect real usage patterns.

Look for assertions on mock call counts or configurations, test-only methods in production classes, and mocks used without understanding the dependency. Check that tests verify real functionality, not implementation details. Refactor tests that assert on mocks to verify actual component behavior instead.