Battery drains after a week of not running

My son has a 97 GMC Sonoma that if he lets it sit for a few days the battery is drained and won't start. I have replaced the battery with a new one. I had 2 different parts stores bench test the alternator and each one came up with everything being at normal performance. I have debated about clipping the vanity lights on the visors since the covers are broken, not sure they shut off correctly. The box is currently unattached due to some work being done on the truck.