XRandR integration tests

[Michael Wyraz]

Hello,

for xrandr exists a specification but the implementation violates it in 
some ways. A good example is 
"https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1113". The 
spec says that a monitor must be deleted if another monitor with the 
same name is added to the screen. There is actually code that does it 
but there's also code that triggers an error before the correct code is 
called.

I think, such a mismatch in behavior could easily be detected by 
integration tests. I have browsed the repo and found a bunch of tests in 
the "tests" but none for xrandr. Is there interest in adding such test?

My idea is to start Xvfb and then run xrandr against it with various 
scenarios.

Kind regards,

Michael.