Clean Code

“Consider the following three laws of Test-driven development (TDD):

• You may not write production code until you have written a failing unit test.
• You may not write more of a unit test than is sufficient to fail, and not compiling is failing.
• You may not write more production code than is sufficient to pass the currently failing test. Test code must be kept as clean as production code. If you don’t keep your tests clean, you will lose them, and without them, you lose the very thing that keeps your production code flexible. It is unit tests that keep our code flexible, maintainable, and reusable. If you have tests, you do not fear making changes to the code. Without tests, every change is a possible bug.”