We all need to know our boundaries! In tests, even more so: boundary conditions are where we often create nasty little defects. The CORRECT mnemonic will help you remember the boundaries you want to consider when writing unit tests.
Now that you’ve learned to test the right thing and how to build high-quality tests, you can start to reap the benefits of lower maintenance costs and fewer defects. However, most code leaves something to be desired when the characters first hit the screen. You need to pay some attention to cleaning it up. You’ll see how in Chapter 8, Refactoring to Cleaner Code, the leadoff chapter in a section on unit testing and design.