Alternator test procedure

Turn the key on, don't start
Pass a piece of ferrous metal in front of alt, - if magnetism strongly sucks the metal to the alternator pulley, the regulator is working.
So is the rotor, brushes, field wire connections.
If it's not putting out decent voltage, (should be 13.8 to 14.2 vdc)
Problem is likely rectifier. ( Diode )
If no magnetism, regulator, brushes, wiring/connections likely the issue.