Is there a way to test the alternator individually or does it require removal and bench tested?

I've heard I can probe the alternator directly to confirm running voltages...can this be done on ours? I don't remember seeing anywhere to probe, but maybe I am wrong.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k