There really isn't any 1st party testing. Some manufacturers have been approved to have 3rd party firewalled testing labs in house. Meaning that no one in the actual manufacturing process or in management has control/influence over the testing lab, nor does anyone that will be receiving the product for example Walmart/Toyrus. It is, the lab, essentially a seperate entity, just housed within the manufacturing facility. This saves Mattel for example time and money.
Since no part of your button is exposed, then I guess you may be safe from testing, but if you can get a GCC , you would be covered in the case someone questioned your covered button.