[tamas]

I had a course that employed the same system. The course wasn't about debuging or real world applications, it was about algorithms. The task was to implement an algorithm correctly. If you did not implement the algorithm correctly, the test cases would fail. If you did not use the correct data structure, the test would time out. That's what it's all about. No specific clues were given so you can't do workarounds taylored to the test cases, or god forbid, hardcode the expected results.

You could do as much testing on your machine as you'd like, with your debugger of choice. And when you are sure you understood the algorithm and implemented it correctly, you can submit.