3 easy tests.
Do all with the car running, turn on every thing electrical you can.
1- DMM on A/C volts. Test at the battery terminals... if you have more than .5 volts you have a diode issue.
2- DMM on D/C volts. Test with one lead on battery + and one lead on alternator B+... this is your voltage drop for the alternator to battery circuit... .5 volts or less is good.
3- DMM on D/C volts. Test with one lead on battery - and one on engine block and then the alternator case... this is your voltage drop for the ground... no more than >5 volts and lower is better. The difference between the drop to the engine block and the drop to the alternator will show if you are getting resistance from paint or corrosion where those parts bolt together (alt is case grounded to the block).
If you like, you can redo #3 while cranking... that would be the heaviest current on the ground... still no more than .5 volts and smaller is better.
If these tests all work fine, I would be inclined to go with the rest of the replies here. My test suggestions should give you some piece of mind in about 2-3 minutes if everything is in good shape.
"Try not to die"