I would connect it up to your battery and then add an increasing amount of load, multiple headlamp bulbs ? In parallel until it energises and switches on and off rapidly. For a quick and dirty test you could momentarily short out the output and see if it operates.
I had some dodgy wiring that fed an aftermarket wiper motor, which shorted out one day when I was testing the lights during the cars recommissioning. They make a right racket when working. I think the cut out current is quoted in the owners manual.