The tests for any flashlight should be to dunk it in the sink and drop it on the floor. If the guts get wet or the flashlight stops working, you probably didn't want to take it on the trail anyway.

I've never placed my faith in one single light. I've got my LED ball cap (unless it's too cold), a waterproofed squeeze light on a breakaway lanyard (part of my wearable essentials kit), and my regular headlamp. I figure that on any trip, one light may die by malfunction or misadventure. Carrying at least one back up ain't ultralight, but I WILL always have light.