The regulator wont behave properly without a battery connected, in fact the excessive ripple voltage can kill the regulator.
the usual way to test an alternator is to switch all electrical loads on for a 5-10 minute period to take the "surface charge "off the battery, and drop the battery voltage down to 12 or so volts,
once the battery is suitably slightly flattened, start the engine and rev it to the approx speed that equates to the speed the alternator is rated at. the alternator should put its maximum rated current into the battery (which is regulated by magnetic saturation of the core) briefly, then as the battery voltage rises the current should fall.
by the time the voltage gets up to 14.4-14.8 volts the voltage regulator will take over and the current should have dropped to a couple of amps.
You cant really use a dummy load its to complicated to be worth bothering.
I am usually not as green as i am cabbage looking.