Use exceptions instead of calling croak()
This little bit of test code was causing me a lot of grief:
You see the regex for qr/Table.1111111111.doesn't exist/? Due to a slight rewording in the error message, that test kept failing. However, it was failing in a way that the following test used to keep failing. As it turns out, I had fixed a bug these tests were designed to catch but it looked at first like I hadn't fixed the bug. Because of the changed error message (and me misreading the test number), I spent a lot of time trying to track down a bug that did not exist.
If I had been throwing proper exceptions, my tests would be trying to validate the class of the exception, rather than the text of the exception. I could have changed my error messages at will without worrying about breaking my tests. Yet another reason why you usually want exceptions instead of calling die or croak.