In this interview filmed during RubyFringe 2008, Luke Francl explains his position towards testing. While supporting unit testing, he thinks testing is not going to reveal all application defects. Development teams should practice code reviews and usability tests which are likely to discover bugs not visible though other methods.
Watch: Luke Francl Explains Why Testing Is Overrated (18 min.)
Most might think that Luke is against testing due to title chosen for his presentation. Luke admits the title of the presentation is a bit misleading because he clearly supports testing. What he wants to say is that testing does not solve all problems. Many bugs cannot or are hard to find though unit tests. He recommends not spending considerable time trying to cover the entire code with tests, and to reserve some time for code reviews and usability testing. Some errors are revealed through code reviews which also helps learning more about programming. Usability testing is also necessary to see how the users perceive the software and how useful is to them.