test-driven-development

Test-driven development starts by writing a failing test that defines expected behavior, then writing minimal production code to pass it, and finally refactoring while keeping tests green. This red-green-refactor cycle ensures every line of code is validated by tests before it exists.

Write a failing test that reproduces the bug, then fix the code to make the test pass. This approach captures the expected behavior permanently, preventing the same bug from reoccurring and catching similar regressions automatically.

Yes. TDD applies to new features, bug fixes, refactoring, and behavior changes. You define each requirement with a failing test first, implement minimal code to satisfy it, then refactor safely knowing tests validate correctness throughout.

Define endpoint behavior with failing tests covering request formats, responses, and edge cases first. Write minimal code to pass each test incrementally. This ensures the endpoint works exactly as specified before release and catches breaking changes early.

TDD requires tests first for production code. Exceptions are limited to throwaway prototypes, auto-generated code, and configuration files, which require human confirmation before skipping test coverage.