Test Driven Development

Test-driven development is a way to write code where you start with a test first. You write a test that shows what you want the code to do. Then you watch it fail. Then you write the smallest amount of code to make it pass. This simple cycle helps you catch mistakes early and build confidence in your work.

Many developers skip tests to save time. But that often leads to bugs and harder fixes later. With test-driven development you always have a safety net. Your tests prove your code works and they stay around to catch future problems. Seeing a test fail first is the key because it shows your test is actually checking something real.

This skill is for anyone who writes code. It works for new features, bug fixes, and even cleanup. Use it every time you change existing code or add something new. The only exceptions are one-time prototypes and generated code. Stick to the cycle of red, green, refactor and your code will be more reliable and easier to change.