How to SimPy simulation code with pytest?

I'm using SimPy to write a simple network simulator. I'd like to write some tests (ideally with pytest or similar) to automatically test that my code is doing what it's supposed to do.

My problem is that the simulation contains a lot of randomly generated events (e.g., flow arrivals). Is it possible to test, for example, if my function that randomly generates new flows works correctly (with pytest)? If so, how?