It also sounds to me like they didn't have any proper unit tests, which is quite a low-hanging fruit for sorting algorithms. Also, while I agree mostly with yo

It also sounds to me like they didn't have any proper unit tests, which is quite a low-hanging fruit for sorting algorithms. Also, while I agree mostly with you, there are cases where logging is more useful for debugging than using step-through debuggers. However, such problems are usually related to concurrency where a debugger may alter or even hide the problem, not stuff like this here.