test-driven-development

Test-driven development guides you to write a failing test first, implement the minimal logic to make it pass, and then clean up the code. This enforces a test-first workflow that reduces regressions and makes behavior changes safer.

The red-green-refactor workflow involves writing a failing unit test, implementing the smallest possible code fix to turn it green, and then cleaning up without changing behavior. This ensures real-behavior tests and minimal code changes.

Yes, you can use test-first development when refactoring existing code. It provides refactoring guardrails by keeping coverage on real behavior, allowing you to change code confidently rather than relying on after-the-fact checks.

The best way to add a feature without shipping unverified code is to define the expected behavior in a test, watch it fail, implement only enough logic to pass, and confirm the test suite stays green throughout the process.

You need to write a failing test before implementation code when adding new features, fixing bugs, refactoring, or changing software behavior. This test-first approach prevents shipping unverified code and reduces regressions.