> Like what are you validating that your tests aren't? Why aren't your tests validating it?

I use use a debugger fairly regularly when I'm writing tests. Debuggers are for moments of incredulity. When a test doesn't behave as I expect, I go back and look at my code. I'll look back and forth, and if I still don't see the root cause, then I'll fire go up gdb instead of adding print statements. Debugging a unit test is often way faster than recompiling.