testing alternator while in car

i dont know how long the alternator has been in there. no idea if its been replaced or not. its lookin ratty.

this and…when i got the car it had an optimum battery in it which ANTLS (fucking homo) said was brand new. so…few days later at work it wouldnt start. so i took the battery out, had it tested and it was dead. got a new battery for the cose of $178. starts great but…my concern was that the other battery died because it was running everything without the alternator and thats y it died so quick. so i wanted to make sure the alternator was ok and i wasnt just running on battery power alone.

u seeeeeee???