test-driven-development

Test-driven development starts by writing a minimal failing test that asserts desired behavior, then implementing the simplest production code to pass it, and finally refactoring while keeping the test green.

The red-green-refactor cycle is a unit testing workflow where you write a failing test, implement minimal code to make it pass, and then refactor while maintaining the green test status.

Yes, TDD applies to bug fixes, refactors, and boundary-case handling by first writing an executable test that captures the expected behavior or reproduces the bug before changing production code.

To ensure code correctness during a refactor, maintain green test status by using existing executable tests as guardrails while you clean up the code without altering its behavior.

You need a testing framework to execute tests and validate code correctness, but the TDD process itself only requires defining a failing test, implementing minimal code, and refactoring.

Writing tests first enforces confidence in code behavior by ensuring every feature has executable guardrails that serve as living documentation and validate expected behavior before implementation.