The problem with tests is that they reflect what the test's author was thinking about. When auditing something you especially look for things the code's author

The problem with tests is that they reflect what the test's author was thinking about. When auditing something you especially look for things the code's author did not consider. If you do your review only based on the tests instead of really thinking the code for yourself, you might very well miss the kind of critical mistakes you should be trying to find.