My car would not start...no battery power at all . My neighbor jumped me...after running a few minutes , he told me to turn on the lights, I did and the car engine immediately died.....and had to be jumped started again.....he says I need a new alternator. Is he right? Is the alternator test Auto Zone does reliable?
I’d certainly start by having both the alternator and battery tested.
When operating with a dead battery the system voltage will be unstable, switching on lights can bring the system voltage below operating level before the alternator can react. I have had engines stall while pulling into the shop by just stepping on the brake pedal (brake lights on).
I suspect your car has been sitting unused for a period of time, recharge the battery with a battery charger.