bug#63198: End-to-end tests Was: bug#63198: cups-service-type uses PAM-enabled 'cups' by default which prevents authentication

[Csepp]

Ricardo Wurmus <rekado@elephly.net> writes:

> I’ll second muradm: these changes broke my printing setup:
>
> * my printer is no longer found because cups-minimal has minimal
>   features and does not include dnssd
> * I cannot add a new printer with ipp://192.168.x.x manually because of
>   authentication problems.  The logs tell me that cups-brf needs to run
>   as root.
>
> As a bonus problem I cannot restart Cups with the “cups” package because
> it cannot be killed.  I disabled the “cups” service and stopped it, but
> cups still runs; killing it is of no use because it’s respawned
> immediately.  Shepherd says it didn’t do it.  I also tried deleting the
> cups socket file, but that also didn’t help.

It might be a good idea to have more end-to-end tests in Guix that would
check if common operations like "finding a printer" work.  It's quite a
bit of up-front effort, but it's better than relying on manual testing
and could make things smoother in the long run.
SUSE has a cool testing framework based on screen captures, maybe it
could be adapted to Guix?