Section 2.4. Testing Software

2.4. Testing Software

Testing a product spans the range from individual developers writing unit tests that check small parts of an application, to system tests that use the whole application, to customers giving feedback about how they really want the product to work. Chapter 6 focuses on testing environments for unit tests and system tests.

One of the cornerstones of the XP (extreme programming) methodology is the importance of extensive unit tests, written even before the functionality that they test has been written. No matter what your methodology or style of programming is, a healthy test suite is good for reassuring yourself that your latest changes haven't broken some other distant part of the product.

Of course, running all those different tests and interpreting their results quickly becomes tedious; if testing is not automated, it is often postponed and then finally abandoned. So it's important when developing and maintaining a product to have a test environment where tests can be added easily and run easily, and where the test results can be clearly understood.