test-driven-development

Test-driven development (TDD) follows a strict RED → GREEN → REFACTOR cycle: write a failing test first, implement minimal production code to pass it, then refactor. This ensures all code has test coverage from the start and prevents untested functionality from reaching production.

Unit testing verifies individual functions or components in isolation, while integration testing validates how multiple components work together. TDD applies both: write unit tests for specific behaviors, then integration tests to confirm components interact correctly across your system.

Yes. TDD works with any testing framework, assertion library, and mocking pattern already in your project. The Skill guides you to identify your project's existing test conventions and apply the RED → GREEN → REFACTOR loop consistently within that environment.

Enforce TDD by requiring a failing test before any production code is written, mandating automated test execution in your CI/CD pipeline, and maintaining code reviews that verify test-first implementation. This prevents untested code and ensures consistent developer workflow.

Start by defining expected request and response flows for your API contract, then write a failing test for a specific behavior (e.g., email validation). Write minimal code to pass that test, refactor, then repeat for additional endpoint behaviors until the full functionality is complete.

Writing a failing test first ensures you understand the requirement before implementing, prevents writing unnecessary code, and guarantees test coverage from day one. This test-first approach enforces code quality and confirms your implementation actually satisfies the intended functionality.