I do wish folks would stop drinking the Kool-ade ...
The test button is NOT the 'determining factor on whether a GFCI works. GFCI's work using a rather simple principle, one that is readily duplicated using simple test equipment. One need not rely only on the test button. (Leaving circuits without ground wires aside).
The statement is correct regarding AFCI's, for reasons that are becoming plainer each day. The primary reason you can't 'test' and AFCI with any certainty the test is any good is because the things are NEVER tested against any sort of an arc.
I will submit the opinion here that science demands that features be readily tested anywhere, anytime, by anyone with repeatable results. Relying upon the 'test' button is a sham- for all we know, the device is a fake and the button but a switch.
I also submit that we should NEVER mention GFCI's and AFCI's together, as if they have anything in common. To do so only sheds doubt on the GFCI.
