The traditional way of testing software encompasses a long phase of manual testing at the end of the software development cycle. This approach has been proven ineffective because manual testing is a long and non-scalable process, and also because the more efficient way is to have short release cycles—two or three weeks—and have a part of the iteration dedicated to the manual testing which, simply isn't affordable. Also, as developers, we realized that the best way of making our code testable is to write simple, granular, and automatic tests while we are still in development. This method, called Test-Driven Development (TDD), was made famous by Kent Beck in his work on Extreme Programming, a revolutionary software programming methodology, revolutionary for its time.
It's based on writing the tests before writing the production code, such as tests that must run automatically using a testing framework. The first framework for doing this was called SUnit because it was...