 <p>It's a good idea to see the coverage of your tests as it can point to problems. If your test code isn't being run then there wasn't much point in writing it!</p> <p>The one I always get is when I give two unit test functions the same name - I add a new test several months after the original and just happen to pick the same name. The unittest framework won't complain about this - one of the functions hides the other and it just won't run one of the tests! The detailed coverage report shows the problem immediately though.</p> <p>If you have other code in your tests that isn't being run then that may also point to other bugs, although typically there's often a couple of lines of boilerplate code that might not get covered depending on how the tests get invoked, so don't obsess about getting to 100%.</p> <p>And if you have test code that really isn't needed any more then it's always good to delete!</p>