I'd like to do testing. The problem is that all the examples of these tests are of modules that work on simple data and produce deterministic outputs. In those cases, I can see how it's easy to set up an automated test.

But a large portion of my code is Monte Carlo, so the only way to see if it works correctly is to evaluate the distribution of the output, which will be correct only in a statistical sense. Moreover, the modules operate on classes with fairly complicated data, so it's difficult to mock up input data without running that part, too.

Why don't anyone show a realistic example of setting up an automated test on a real-life piece of software?