What should you test? Before you begin, write a list of all the tests you know you will have to write. The first part of our approach to dealing with programming stress is never to take a step forward unless we know where our foot is going to land. When we sit down to a programming session, whit is it we intend to accomplish?

There is evidence that doing TDD takes about 15% longer than not doing TDD (George and Williams 2003). But there is also evidence that TDD leads to fewer defects. Two studies at Microsoft found that the number of bugs found went down by 24% and 38% with the use of TDD (Sanchez, Williams, and Maximilien 2007, 6). So, yes, TDD may take longer initially, but the time will come back to the team in the form of reduced bug fixing and maintenance time.