test-driven-development

Test-driven development prevents regressions by writing executable tests before production code, creating a living documentation of behavior that guards against future failures across feature development and refactoring.

To apply red-green-refactor, write a failing test for the desired behavior, implement the minimal production code to pass that test, and finally refactor the code for readability and safe, incremental changes.

Yes, test-first discipline applies to bug fixes and refactoring by clarifying expectations through tests-first validation, which reduces debugging time and catches regressions early across existing codebases.

The best way to start writing tests before implementation is to define a failing test for the exact behavior change, ensuring the tests guide your software design and keep production code minimal.

Test-driven development keeps production code minimal by enforcing a tests-first workflow where you only write the code necessary to pass the failing test, reducing unnecessary complexity and debugging time.