I'm going to assume that we can't test probing functions using the simulator since probing is handled by the motion controllers.
But I'll ask anyway.  Can we test probing in the SIM?
I've mapped all 4 probe inputs to CNTL + P on my keyboard to test a tool setter probing cycle, that works just fine,
However, when I run the cycle, it doesn't run the G31.  Again, I assume this is because I'm running the simulator.

Okay,
So I just found out that I can test probing.  I forgot to put a feedrate in my probe move.  
However, it didn't register my simulated probe strike, it simply read the end of my probe move.  
Not exactly what I wanted, but it does allow me to test my code.