Testing

Abstract

Historically, testing and performance are activities saved for the end of a project. For example, testing is the last step of a project in the traditional waterfall approach. But agile methodologies such as Extreme Programming (XP) have proven that testing-and-performance checking early and often leads to better quality software. Testing and performance checking from day one of development can help developers to locate defects and bottlenecks when they’re introduced, thereby reducing the time and expense of correcting them. In addition, unit testing improves the refactoring and debugging process. Automated unit testing supports refactoring by quickly determining how small changes affect the entire system. Debugging becomes more challenging as applications grow in size. Debugging failed unit tests rather than debugging entire applications can save valuable time.

“Whenever you are tempted to type something into a print statement or a debugger expression, write it as a test instead.”

—Martin Fowler

Refactoring: Improving the Design of Existing Code (Reading, MA: Addison-Wesley, 1999).