It's spec'd in the Service Manual, but I'm not at that PC so I can't pull it up.
I'd rather fight with the dealer for 10 minutes than have to find a tow truck in the middle of the night on some distant highway.
Might be good to put together a version of this diagnostic process using a common multimeter. The automated system Nissan uses, just compares known voltage ranges over time to what's measured and gives an idiot display to the tech.
For example, excess ripple is a result of failing diodes, I would expect. Whereas other voltage problems could be the regulator.
Both items are separate from each other, but built into the alternator, as the SM shows them as distinct items in the exploded diagram. I haven't looked to see if they're replaceable without removing the alternator. In fact, I haven't even looked to see where the alternator is, under the hood!
I haven't had the time to distill a simple test procedure, so if someone else wants to give a shot, go for it!