Re: [PATCH v2 04/29] tests/acceptance: Use 'version-min' tag to verify QEMU binary version

From: Eduardo Habkost <ehabkost@redhat.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>
Cc: Cornelia Huck <cohuck@redhat.com>,
	Markus Armbruster <armbru@redhat.com>,
	Wainer dos Santos Moschetta <wainersm@redhat.com>,
	qemu-devel@nongnu.org, Denis Plotnikov <dplotnikov@virtuozzo.com>,
	Cleber Rosa <crosa@redhat.com>
Subject: Re: [PATCH v2 04/29] tests/acceptance: Use 'version-min' tag to verify QEMU binary version
Date: Thu, 30 Jan 2020 15:40:56 -0500	[thread overview]
Message-ID: <20200130204056.GH25446@habkost.net> (raw)
In-Reply-To: <1eee2851-8b65-8343-2847-1e6634bae46f@redhat.com>

On Thu, Jan 30, 2020 at 06:18:22PM +0100, Philippe Mathieu-Daudé wrote:
> Cc'ing Markus
> 
> On 1/30/20 6:08 PM, Cornelia Huck wrote:
> > On Thu, 30 Jan 2020 14:28:19 +0100
> > Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
> > 
> > > On 1/30/20 1:26 PM, Cornelia Huck wrote:
> > > > On Wed, 29 Jan 2020 22:23:20 +0100
> > > > Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
> > > > > Introduce the 'version-min' tag.
> > > > > Tests can set it to the minimum version of QEMU they require.
> > > > > If QEMU is older, the tests will be cancelled (skipped):
> > > > > 
> > > > >     $ python -m avocado --show=app run tests/acceptance/x86_cpu_model_versions.py
> > > > >      (01/11) X86CPUModelAliases.test_4_0_alias_compatibility: CANCEL: Test expects version '4.1' but QEMU binary is '3.1.1' (0.10 s)
> > > > >      (02/11) X86CPUModelAliases.test_4_1_alias: CANCEL: Test expects version '4.1' but QEMU binary is '3.1.1' (0.10 s)
> > > > >      (03/11) X86CPUModelAliases.test_none_alias: CANCEL: Test expects version '4.1' but QEMU binary is '3.1.1' (0.10 s)
> > > > >      ...
> > > > > 
> > > > > Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> > > > > ---
> > > > >    tests/acceptance/avocado_qemu/__init__.py | 18 ++++++++++++++++++
> > > > >    1 file changed, 18 insertions(+)
> > > > 
> > > > Hm... this might cause headaches if someone tries to backport tests on
> > > > distro versions; but we probably won't be able to test for the feature
> > > > in many cases anyway?
> > > 
> > > Are you saying a distro version might not match upstream version when a
> > > feature is introduced? Isn't it the point of versioning? If you are
> > > thinking of some case you point me at it so I can improve this patch?
> > 
> > Something like the following:
> > 
> > - a feature together with a test is introduced in QEMU version n
> > - a distro is using m (where m < n), but wants the new feature and
> >    backports it
> > 
> > If that distro now wants to include the acceptance test as well (to run
> > in their internal testing), they need to adapt the version check as
> > well, or the test simply won't run. Depending on how this is reported,
> > it might not be easily noticed. If the test depends on another feature
> > (but the feature does not), it might get a bit more complicated.
> > 
> > It's probably not a big problem, but I wanted to point it out.
> 
> OK now I understand better.
> 
> I wrote that patch having QAPI versioned features in mind, which are
> versioned/documented.
> For example:
> 
>   ##
>   # @qom-list-types:
>   #
>   ...
>   #
>   # Since: 1.1
> 
> Now it is true that we add a new feature to a device, we do not document
> that in QAPI, and I don't see how we can test it via QMP.

The features are documented as introduced in specific QEMU
versions to help humans, but the best way to test for their
existence is to check the QAPI schema.

-- 
Eduardo