test-driven-development

Test-driven development prevents bugs by mandating the creation of failing tests prior to writing any production code. It ensures code reliability and makes refactoring safer through the iterative Red-Green-Refactor cycle.

To implement a feature using the Red-Green-Refactor cycle, you first write a failing test that defines the desired behavior. Next, you write minimal production code to pass that test, and finally clean up the code without changing its functionality.

You should write tests before writing production code when developing new features, fixing bugs, or refactoring. This test-first approach ensures code quality and prevents regressions by verifying expected outcomes before implementation begins.

Yes, test-driven development works for fixing existing bugs in agile workflows by guiding developers to write a failing test that reproduces the bug before applying the fix. This ensures code reliability and prevents future regressions.

The best way to ensure code quality for a user authentication feature is using test-driven development. You first write a test asserting invalid logins fail, confirm it fails, and then write the code handling invalid credentials to make it pass.