Testing Test Writing

Prioritize tests for critical user flows and behavior over implementation details. Focus on the happy path and common failure scenarios first, deferring edge cases until later to balance testing velocity with development speed.

Unit tests verify individual components in isolation, while integration tests validate how components work together. Choose unit tests for fast feedback on logic; use integration tests for critical user flows that span multiple components.

Use clear, descriptive test names that explain what behavior you're testing from the user's perspective, not implementation details. Name tests to reflect the outcome or scenario, making failures immediately understandable.

Implement mocks to isolate the code under test from external systems, enabling fast execution and reliable results. Mock external dependencies in unit tests; use real integrations in integration tests for critical user flows.

Testing behavior ensures your tests reflect what users actually need, remaining stable across refactoring. Implementation-focused tests break unnecessarily during rewrites, creating maintenance burden without protecting real value.

Locate tests under a tests/ directory with clear structure. Organize by feature or module so tests are discoverable, maintainable, and clearly separated from production code.