Writing Good Tests

Philosophy

"Write tests. Not too many. Mostly integration." — Kent C. Dodds

Tests verify real behavior, not implementation details. The goal is confidence that your code works, not coverage numbers.

Core principles:

1. Test behavior, not implementation — refactoring shouldn't break tests
2. Integration tests provide better confidence-to-cost ratio than unit tests
3. Wait for actual conditions, not arbitrary timeouts
4. Mock strategically — real dependencies when feasible, mocks for external systems
5. Don't pollute production code with test-only methods

Test Structure

Use Arrange-Act-Assert (or Given-When-Then):