This is why I tend towards being a strong advocate of a "test group" for any software shop. This is basically a group of people running a combination of manual

This is why I tend towards being a strong advocate of a "test group" for any software shop. This is basically a group of people running a combination of manual and automated tests against software as a black box. Unit tests never catch everything. The problem with them is they can only test everything the coder thought to test. There is value in testing all of those things the coders never thought of.