I test them with my hands, and do a walk through to see if it stops the door.
I’m not in favor of the 2"X 4" because I don’t want to buy a door.
With hands it’s not likely to cause damage, unless your a lessron and try to push it back up instead of just applying a little resistance.
If it’s an old unit I just walk through to see if the sensor is working.
( lessron )= Someone that does not qualify to be a moron.
Someone mentioned that the pressure should be approximately equivalent to the weight of a gallon of water/milk. Inspectors can practice using that as an amount to cause it to reverse. Anymore and they should let it go to prevent damage.
Before you test them make sure there is a bracket and not just lag screws into the thin door metal securing the arm to the door.