no, unit testing doesn't tell you if your constructs aren't safely composable. So: it will pretty much never find a threading bug, a concurrency bug, a reentran

no, unit testing doesn't tell you if your constructs aren't safely composable. So: it will pretty much never find a threading bug, a concurrency bug, a reentrancy bug, etc. I only know three ways to detect this sort of bug, and they all suck: 1) get smart people to stare at all of your code 2) brute force as many combinations as possible 3) move the problem into the type system of your language so you can do static analysis of the code