test-driven-development

Test-driven development starts by writing a failing test that defines expected behavior before any production code. You then write minimal implementation code to pass that test, ensuring the feature works as intended from the outset.

The Red-Green-Refactor cycle is an iterative testing process. You write a failing test, create minimal code to pass it, and then clean up the code through refactoring to ensure software quality and prevent regressions.

Test-driven development prevents bugs during refactoring by enforcing a rigorous testing methodology. By mandating failing tests before implementation, it establishes a safety net that catches regressions immediately when you modify existing code.

Test-driven development is applicable to all code development, including new features, bug fixes, and refactoring. It enforces writing tests that define expected behavior before writing the minimal code required to pass them.

Writing a failing test before production code is the Iron Law of test-driven development. It ensures you only write code necessary to meet defined behavior, preventing untested code from introducing bugs and making refactoring safer.