While that is an excellent suggestion, it may be difficult if you do not have an adapter for the molex connector.
Put a voltmeter on it and see if reads 18-20 Volts AC. Then short the output and make sure the breaker opens immediately.
Pete
Do what Norton suggested. Connect the wires to the middle and lower prongs on the molex connecter like in the picture.
(Picture not mine) Look to the right of the UL label. Follow up by shorting the wires once connected. The circuit breaker should trip very quickly.