How do I check the regulator on a 1340cc Harley Davidson motor to see if its bad or good!?

I was told to check the regulator first before pulling the alternator out! I did the old unhook cables n if bike stays running its the battery! Well it died so its either the alternator or the regulator is what I was told! Tried to call dealership or a mechanic shop n unfortunately there are none open on sundays! Just was wondering if anyone out there could help me so I can get to riding! I have a continuity light tester n a ohms meter! Thanks to anyone that can help or try n help me out! Travis