test-driven-development

Test-driven development follows the red-green-refactor cycle: write a failing test first, run it to confirm failure, implement minimal code to pass the test, verify all tests pass, then refactor while keeping tests green. This workflow ensures code changes are validated by tests before release.

Test-driven development requires writing a failing test before any production code exists. This contrasts with writing code first and testing afterward. Writing tests first ensures requirements are clear, forces modular design, and catches bugs earlier in the development cycle.

Test-driven development applies across feature implementation, bug fixes, and refactoring tasks to uphold the red-green-refactor discipline. It's most effective when you need reliable software with clear specifications and want to prevent regressions during code changes.

Execute your test suite after writing minimal production code. When all tests pass with a green status, your implementation meets the test requirements. This verification step confirms the code change is valid before proceeding to refactoring.

Yes—refactoring in TDD means improving code structure while keeping the full test suite green. All tests must pass before and after refactoring to ensure behavior is preserved. This safety net makes code cleanup and optimization low-risk.