gpio smoke test needs to test exceeding the number of edge pins

[tve]

Write a test that exceeds the number of gpio pins with edge detection and verify that the error message makes sense.

[maruel]

I think https://github.com/google/periph/blob/master/conn/gpio/gpiosmoketest/gpiosmoketest.go#L202 does what you ask for, is it right?

[maruel]

I'll close since periph/host#39 will change the dynamics a lot. Let's file an issue at https://github.com/periph/host if we should add this.