If you added code to tickle the GPIO specifically to gain insight into the process, whether you leave it in or not, then it’s “print debugging”. Many a microcon

If you added code to tickle the GPIO specifically to gain insight into the process, whether you leave it in or not, then it’s “print debugging”. Many a microcontroller developer has tickled an indicator LED in their day. If your simply monitoring activity through an external source (whether it’s an oscilloscope or watching traffic through a network analyzer) then that’s basically black box testing.