Adding Tests to Your Claude Code Project

Most Claude Code projects ship with zero tests. This means every change is a gamble — you might fix one thing and break three others without knowing until a user reports it. Tests are automated checks that verify your app works correctly. They run in seconds and catch bugs before your users do.

Claude sometimes generates tests, but they tend to test implementation details rather than behavior. Refocus tests on observable outcomes. Add integration tests for API endpoints and E2E tests for critical paths

Refactor existing tests to test behavior, not implementation. Add API integration tests with realistic payloads. Test error handling paths. Add load tests for data processing endpoints to verify memory handling

Unit tests check individual functions in isolation — does this function calculate the right total? Integration tests check that multiple pieces work together — does submitting this form save to the database? End-to-end (E2E) tests simulate a real user — can someone sign up, log in, and complete a purchase? Start with E2E tests for your most critical flows, then add integration tests for your API endpoints.

Set up your tests to run automatically on every code push using GitHub Actions or a similar CI service. This way, you'll know immediately if a change breaks something. A basic CI pipeline runs your tests, checks for TypeScript errors, and builds the project. If any step fails, the push is flagged before it reaches production.