openQA vs. Rawhide

[Adam Williamson]

On Tue, 2015-07-07 at 08:16 -0700, Adam Williamson wrote:
> Hey, folks. Just to let everyone know, I started looking into why
> openQA tests are failing in Rawhide yesterday but got sidetracked
> trying to get rid of a bunch of rice weevils in my kitchen. 
> (seriously,
> those little buggers are a pain in the rear end).
> 
> I'm not sure what's going on with the 'Begin Installation' button
> apparently not becoming available in boot.iso , but I know
> approximately what's wrong with the live install: the fonts have
> somehow changed on some (all?) pages. On the root and user creation
> screens at least, the text it's trying to match now looks 
> sufficiently
> different (a pixel taller, for one thing) that the match fails. I've
> written a new needle for the root screen, but I wanted to try and see
> if I could find out what actually happened to cause the text to look
> different before we go and create new needles for every text match in
> the installer...

So I got a bit farther with this today. The difference actually seems
to be not 22 vs. 23 but boot.iso vs. Workstation live. There's some
kind of rather subtle difference in font rendering between the two. The
easiest way to see it is to look at a Done button. On boot.iso (22 or
Rawhide), the 'D' is 11 pixels tall. On Workstation live images, it's
10 pixels tall. There are other differences too, if you look closely:
the capital 'R' and 'P' in 'Root Password' (on the root password
screen) are 9 pixels high on Workstation live images, 10 pixels high on
boot.iso.

Now the question is do we:
i) try and figure out what the hell the difference between the two is -
which could be a hell of a yak shave 

ii) try and finesse the needles (match area, size, required similarity
%age) until openQA is OK with the differences

iii) have two variants of affected needles?

In any case it's something we need to be aware of when using text
needles in anaconda - please check your needles work with both boot.iso
and live images...

I did try a *bit* of i). I know one obvious difference is that gnome
-settings-daemon is active on the Workstation live, but not on boot.iso
, and I know g-s-d does set various font options. The most obvious one
that might differ is the hinting strength, but actually the default for
that seems to be 'medium' both in the g-s-d dconf schema and in
/etc/X11/Xresources (which I think sets the default if g-s-d isn't
involved).

I can't reproduce the boot.iso 'look' by messing with the hinting and
antialiasing settings in gnome-tweak-tool on a live image - I can
certainly make the rendering look different, but no combination of
settings seems to make it look exactly like boot.iso.

An interesting case I just discovered is that if I set GNOME's 'text
scaling factor' to 1.01 on the Workstation live, it makes the glyph
heights the same as in boot.iso, but there are still some very subtle
differences in the rendering: for e.g. the kerning is a bit different
(there's a one pixel gap between the 'D' and the 'o' of 'Done' in
Workstation-at-1.01 while on boot.iso there's no gap).

a KDE live image has the same rendering as boot.iso, which is about
what I'd expect (as g-s-d is not active there either).
-- 
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Twitter: AdamW_Fedora | XMPP: adamw AT happyassassin . net
http://www.happyassassin.net