[lmi] Xvfb and xvfb-run defaults differ [Was: Headless GUI tests on corporate server]

[Greg Chicares]

On 11/13/21 11:45 PM, Greg Chicares wrote:
[...]
> I decided to use "the default screen configuration"
> from the manpage:
> 
> https://linux.die.net/man/1/xvfb
> |
> | Xvfb -pixdepths 3 27 -fbdir /var/tmp
> |    The server will listen for connections as server number 0,
> |    will have the default screen configuration (one screen,
> |    1280x1024x8), will also support pixmap depths of 3 and 27,
> |    and will use memory mapped files in /var/tmp for the
> |    framebuffer. 

However, the 'xvfb-run' script uses a different default:

  $grep '[0-9]x[0-9]' `whence xvfb-run`
  XVFBARGS="-screen 0 1280x1024x24"

and, as we've seen, this:
  Xvfb :1 -screen 0 1280x1024x8 &
turned out to be problematic, whereas this:
  Xvfb :1 -screen 0 1280x1024x24 &
worked.

I already knew that using the 'xvfb-run' script is more convenient
and robust than emulating it manually; now I've also learned that
it can accept 'Xvfb' arguments such as '-fbdir':

xvfb-run --server-args="-fbdir /var/tmp" wine /opt/lmi/bin/wx_test.exe 
--ash_nazg  --data_path=/opt/lmi/data --test paste_census

which enables this command to show the framebuffer screen:

xwud -in /var/tmp/Xvfb_screen0

in a 'bullseye' chroot where the 'paste_census' test fails.