Can you trust the test & reset buttons on a GFCI?

The biggest single hazard (IMHO) that GFI breakers protect against is the connection between small appliance and water..... so if your toaster falls in the sink you don't get shocked. OR if your child or grandchild decides to see if the hairdryer will blow bubbles. Thus the code requirements that receptacles above a countertop with a sink be GFI protected.