“Test code is just as important as production code. It is not a second-class citizen. It requires thought, design, and care. It must be kept as clean as production code….It is unit tests that keep our code flexible, maintainable, and reusable. The reason is simple. If you have tests, you do not fear making changes to the code! Without tests, every change is a possible bug. No matter how flexible your architecture is, no matter how nicely partitioned your design, without tests you will be reluctant to make changes because of the far that you will introduce undetected bugs.”
Frances M. Advincula 