But if it fails the test you probably don’t want to use the charger anyway.

And if it passes the test?

 

The there would likely not be any damage from the test. The lack or an arc between traces would have resulted in a failure.

Edit: would result in the unit passing….

 

I just try to use name brand USB chargers. There's plenty at thrift stores and yard sales, though you do have to be wary of the white Apple cubes, which are popular enough to be counterfeited.