Thats how i tested mine. Took two wires attached them to the battery in my truck, and touched the contacts on the motor. If memory serves me right, the one terminal that is by itself is the ground. The other two are for the two speeds. If she cranks, she's good.
While we're on the subject, The wiper motor on my 69 works but the arms do not return to their "home" position when I turn them off. They just stop where ever I turn them off at. What could that mean? Switch or motor??