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Friday, April 29, 2011


Even good programmers make mistakes. The difference between a good programmer and a bad programmer is that the good programmer uses tests to detect his mistakes as soon as possible. The sooner you test for a mistake the greater your chance of finding it and the less it will cost to find and fix. This explains why leaving testing until just before releasing software is so problematic. Most errors do not get caught at all, and the cost of fixing the ones you do catch is so high that you have to perform triage with the errors because you just cannot afford to fix them all.
Testing with PHPUnit is not a totally different activity from what you should already be doing. It is just a different way of doing it. The difference is between testing, that is, checking that your program behaves as expected, and performing a battery of tests, runnable code-fragments that automatically test the correctness of parts (units) of the software. These runnable code-fragments are called unit tests.
The goal of using automated tests is to make fewer mistakes. While your code will still not be perfect, even with excellent tests, you will likely see a dramatic reduction in defects once you start automating tests. Automated tests give you justified confidence in your code. You can use this confidence to take more daring leaps in design (Refactoring), get along with your teammates better (Cross-Team Tests), improve relations with your customers, and go home every night with proof that the system is better now than it was this morning because of your efforts.

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