[libvirt] [PATCH 0/3] libxl: Add a test suite for libxl_domain_config generator

[Marek Marczykowski-Górecki]

On Fri, Jul 14, 2017 at 05:59:57PM -0600, Jim Fehlig wrote:
> On 07/01/2017 08:16 PM, Marek Marczykowski-Górecki wrote:
> > On Sun, Feb 26, 2017 at 07:02:24PM -0700, Jim Fehlig wrote:
> > > Long ago danpb posted some patches to test libvirt domXML to
> > > libxl_domain_config conversion
> > > 
> > > https://www.redhat.com/archives/libvir-list/2014-May/msg01102.html
> > > 
> > > Some of the prerequisite patches were pushed, but we've never managed
> > > to push patches actually providing the conversion tests. I sent several
> > > follow-ups to Dan's work but never converged on a satisfactory solution
> > > for all the Xen versions supported by libvirt. The last attempt was in
> > > Sept 2014
> > > 
> > > https://www.redhat.com/archives/libvir-list/2014-September/msg00698.html
> > > 
> > > I tried to revive the work in Jan 2015, but that also stalled
> > > 
> > > https://www.redhat.com/archives/libvir-list/2015-January/msg00924.html
> > > 
> > > Fast-forward over 2.5 years from the first attempt and libvirt no longer
> > > supports older Xen versions 4.2 and 4.3 that were proving to be problematic.
> > > Starting with Xen 4.5 libxl added support for libxl_domain_config_from_json,
> > > which provides a way to implement the conversion tests that work with all
> > > Xen versions >= 4.5 (including latest xen.git master).
> > 
> > Few more months have passed...
> 
> And a few more weeks :-). Sorry for the delay. Slowly catching up on libvirt
> mail after some time away...

It's me this time...

> > FWIW, I've tested it with Xen 4.6. The patch needs very minor update:
> >   - s/VIRT_TEST_MAIN_PRELOAD/VIR_TEST_MAIN_PRELOAD/
> >   - add xencaps argument to libxlBuildDomainConfig cal >
> > 
> > After that, it works! When I made some test to fail, reported error is
> > not so helpful ("libvirt: Xen Light Driver error : internal error:
> > Expected and actual libxl_domain_config objects do not compare"), but it
> > do catch failures.
> > Then, if I change strcmp to virTestCompareToString, the output is much
> > more helpful.
> 
> Thanks for the improvements. I noticed you included them in your V2 of patch
> 3/3. I assume you needed patches 1 and 2 as well?

Yes, in this tests shape. But see below.

> > I'd really love to have it merged, mostly because I want to add more tests
> > using this framework (see "Add setting CPU features (CPUID) with
> > libxenlight driver" thread).
> 
> I really dislike patches 1 and 2. They remove very useful checks IMO.
> Shortly after posting the series in Feb, I tried mocking the emulator
> checks. I failed quite a bit before coming up with something that worked,
> yet not so satisfying :-). I'll attach the (now rather old) patches for
> reference.

My independent try to this test approach ("tests: check domain XML to
libxl structures conversion") had much simpler (but uglier) solution for
this problem: use /bin/true as emulator path (replaced in runtime, just
after loading XML from file). While proper mocking this check would be
better, apparently it isn't trivial.

> > Is there anything I can do to make it happen?
> 
> Do you have time to update these old patches, test, and repost to the list?
> Or perhaps have better ideas on mocking, or approaches that avoid the need
> for 1/3 and 2/3.

If using /bin/true as emulator path is acceptable, I can finish this and
post updated version.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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