Re: [Qemu-devel] [PATCH v4 4/5] iotests: Add VMDK tests for blockdev-create

[Eric Blake]

On 12/7/18 10:42 AM, Kevin Wolf wrote:
> Am 07.12.2018 um 16:40 hat Eric Blake geschrieben:
> > On 12/7/18 8:45 AM, Kevin Wolf wrote:
> > > Am 07.12.2018 um 14:12 hat Markus Armbruster geschrieben:
> > > > git-am complains
> > > >
> > > >       Applying: iotests: Add VMDK tests for blockdev-create
> > > >       .git/rebase-apply/patch:281: trailing whitespace.
> > > >                   format:
> > > >       .git/rebase-apply/patch:308: trailing whitespace.
> > > >                   format:
> > > >       .git/rebase-apply/patch:335: trailing whitespace.
> > > >                   format:
> > > >       .git/rebase-apply/patch:600: new blank line at EOF.
> > > >       +
> > > >       warning: 4 lines add whitespace errors.
> > >
> > > This is in the reference output, so trailing whitespace/blank lines are
> > > actually correct.
> >
> > Ah, but doesn't ./check already ignore differences in trailing whitespace
> > present in the actual running that is not present in the *.out files,
> > precisely so we don't have to check in trailing whitespace reference
> > outputs?
>
> It does ignore whitespace changes, so even if we remove that whitespace,
> the test won't fail. But I don't think that's a good reason to check in
> inaccurate reference output.
>
> There are a few test cases that have a reference output like this and
> it's always annoying: When I later add a new subtest, I add the new test
> code, review the ./check output and if it looks good, I do something
> like 'cp 237.out.bad 237.out'. At that point, I'll have to manually
> revert completely unrelated whitespace changes again.

Is it worth teaching iotests.img_info_log() to strip trailing 
whitespace?  Or even to teach qemu-img itself to quit generating 
trailing whitespace?

> Some 'git am' warnings feel like the lesser evil to me.

True, and a comment in the commit message about intentionally triggering 
a known checkpatch flag goes a long ways to document why you want the 
trailing whitespace (assuming we don't instead decide to tackle a root 
cause of having the whitespace in the first place).

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org