test-driven-development

Test-first development prevents regressions by forcing a failing unit test to exist before any production code is written. You implement the smallest amount of code to pass the test, ensuring correct behavior and reducing production risk.

To start test-first development, write a failing unit test that defines the desired feature behavior. Next, implement the minimal production code required to make that test pass, then refactor the code to clean it up while keeping the test green.

Yes, test-driven development applies to any language or tech stack. The methodology is tech-agnostic, allowing you to use the red-green-refactor workflow for feature development, bug fixes, and refactoring across any platform where unit testing is supported.

The best way to refactor without changing behavior is using test-first unit tests as living documentation. Running focused tests as you code verifies existing behavior remains intact, enabling confident code cleanup and reducing regression risk during structural changes.

You should avoid a test-first approach in scenarios where reliability and maintainability do not matter, or when rapid prototyping requires exploring designs before defining behavior. Without a clear expected outcome, forcing a failing unit test adds unnecessary overhead.