Snap-On makes an actual bench top chamber where a TPM can be live tested. I don't know of any device which can do a complete function test other than that. We have devices which can query a monitor, basically tell it to wake up and talk to me, but until it's installed under pressure you never know for sure if everything works.
I'd go ahead and install the monitors. If one is no good the car will tell you which one and you can just pop the bead on one side of that wheel and install another monitor without having to rebalance the wheel.