Test them under ridiculous load. 120% of peak voltage, huge ripple, let them get nice and toasty. The bad caps will pop in minutes, a good one can survive for weeks.
The problem is that the prototypes you get from your Chinese manufacturer will be made with top quality Japanese components. They'll switch them for the cheap junk later while you're not looking, about a 10th of the way into your 1 million unit production run.
The problem is that the prototypes you get from your Chinese manufacturer will be made with top quality Japanese components. They'll switch them for the cheap junk later while you're not looking, about a 10th of the way into your 1 million unit production run.