test-driven-development

Test-driven development prevents regressions by mandating the creation of failing tests before writing production code, ensuring all subsequent code changes are continuously verified against expected behavior.

The Red-Green-Refactor cycle in TDD is the core loop of writing a failing test, creating minimal production code to make it pass, and then refactoring the code while ensuring behavior remains verified.

To apply TDD when fixing bugs or adding new features, you must first write a failing test that defines the expected behavior, then implement the minimal code required to pass that test before refactoring.

Yes, you can use test-driven development for agile refactoring tasks, as it enforces writing tests to verify existing behavior before modifying production code, thereby preventing regressions during structural improvements.

You must write a failing test before production code to strictly enforce the TDD methodology, ensuring the test accurately captures requirements and validates behavior from the very start of development.