Improve yast2_samba.pm

[Zaoliang]

• use "dmesg -n 4" against kernel message floating over console
• use wait_screen_change to avoid timeout issue
• see ticket for more information: https://progress.opensuse.org/issues/19922
• see my reference tests:
  openSUSE TW: http://e13.suse.de/tests/3730#step/yast2_samba
  openSUSE Leap: http://e13.suse.de/tests/3731#step/yast2_samba
  SLES 12 SP3: http://e13.suse.de/tests/3750#step/yast2_samba

[rwx788]

I can confirm that test module is stable and main reason of failures are kernel messages disrupting ncurses ui, however on production there were other failures, like:
https://openqa.opensuse.org/tests/435819#step/yast2_samba/29

The main problem with tests (independent from other sources of instability) is that we do a lot of key presses and do not verify what happened. So I would spend more time trying to eliminate potential issues we have already seen.

[okurz]

I only see a dmesg call so the commit and PR description does not fit the content

[Zaoliang]

@okurz it seems that the changes got somehow lost, I'm checking this...

[Zaoliang]

@okurz got lost changes back :)

[okurz]

no wait_screen_change before assert_screen

[okurz]

also this should not be necessary when we have a wait_serial just afterwards

[rwx788]

As we see a lot of failures related to the fact that return code is not there after 60 seconds, I suggest that we increase it to some bigger value, e.g. 180.

[Zaoliang]

@rwx788 as we talked already, there is no issue related to timeout (wait_serial) at moment. Since a couple of days I have sometimes failures for samba because of yast2 got crashed. I've reported the issue:
https://bugzilla.opensuse.org/show_bug.cgi?id=1051169

[okurz]

@rwx788 should we mark the dmesg with a soft fail?

[rwx788]

@okurz sounds good to me. But we need to make up our mind about this in general. Adding "quiet" to boot option should do the trick, for example:
console_loglevel
Only messages with a log level lower than this value will be
printed to the console. The default value for this field is
DEFAULT_CONSOLE_LOGLEVEL (7), but it is set to 4 if the kernel
command line contains the word "quiet", 10 if the kernel
command line contains the word "debug", and to 15 in case of a
kernel fault (the 10 and 15 are just silly, and equivalent to
8). The value of console_loglevel can be set (to a value in
the range 1-8) by a syslog() call with a type of 8.
@Zaoliang here is the bug reference: https://bugzilla.suse.com/show_bug.cgi?id=1011815

[okurz]

ok, I added an according comment to https://progress.opensuse.org/issues/19398 . That should be good enough for now