Actually we test the hall effect with the distributor right in the car. Most shops have this tester that have adapters for the different distributors and they plug right into the ignition module. The engine is then cranked and the blinking light on the tester will let you know if the unit is bad or good. I imagine to test the distributor out of the car you could place the distributor in a vice then hook up the tester to a 12 volt battery source and spin the distributor gear by hand and also get a reading. Fords seem to be the most problematic in this area. GM's second place.
