Alternator woes

[cpginkpt]

so basically just perform these tests (?) => https://www.wikihow.com/Check-an-Alternator

If it DOESN'T pass the voltage tests how can I be sure it is the alternator and not the wiring harness/fusible link/other crispy wiring issues that may be feeding the alternator?

I am also getting a whine from the engine compartment (hard to pinpoint) which combined with the Christmas lights point pretty firmly in the direction of a new alternator.

I just don't want to jump to that conclusion without ruling out other components like the wiring harness etc.