Re: [PATCH v2 00/23] Convert avocado tests to normal Python unittests

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, Jul 25, 2024 at 08:42:31PM +1000, Richard Henderson wrote:
> On 7/25/24 19:55, Daniel P. Berrangé wrote:
> > On Thu, Jul 25, 2024 at 09:35:22AM +1000, Richard Henderson wrote:
> > > On 7/25/24 03:52, Thomas Huth wrote:
> > > > The Avocado v88 that we use in QEMU is already on a life support
> > > > system: It is not supported by upstream anymore, and with the latest
> > > > versions of Python, it won't work anymore since it depends on the
> > > > "imp" module that has been removed in Python 3.12.
> > > > 
> > > > There have been several attempts to update the test suite in QEMU
> > > > to a newer version of Avocado, but so far no attempt has successfully
> > > > been merged yet.
> > > > 
> > > > Additionally, the whole "make check" test suite in QEMU is using the
> > > > meson test runner nowadays, so running the python-based tests via the
> > > > Avocodo test runner looks and feels quite like an oddball, requiring
> > > > the users to deal with the knowledge of multiple test runners in
> > > > parallel (e.g. the timeout settings work completely differently).
> > > > 
> > > > So instead of trying to update the python-based test suite in QEMU
> > > > to a newer version of Avocado, we should try to better integrate
> > > > it with the meson test runner instead. Indeed most tests work quite
> > > > nicely without the Avocado framework already, as you can see with
> > > > this patch series - it does not convert all tests, just a subset so
> > > > far, but this already proves that many tests only need small modifi-
> > > > cations to work without Avocado.
> > > > 
> > > > Only tests that use the LinuxTest / LinuxDistro and LinuxSSHMixIn
> > > > classes (e.g. based on cloud-init images or using SSH) really depend
> > > > on the Avocado framework, so we'd need a solution for those if we
> > > > want to continue using them. One solution might be to simply use the
> > > > required functions from avocado.utils for these tests, and still run
> > > > them via the meson test runner instead, but that needs some further
> > > > investigation that will be done later.
> > > > 
> > > > 
> > > > Now if you want to try out these patches: Apply the patches, then
> > > > recompile and then run:
> > > > 
> > > >    make check-functional
> > > > 
> > > > You can also run single targets e.g. with:
> > > > 
> > > >    make check-functional-ppc
> > > > 
> > > > You can also run the tests without any test runner now by
> > > > setting the PYTHONPATH environment variable to the "python" folder
> > > > of your source tree, and by specifying the build directory via
> > > > QEMU_BUILD_ROOT (if autodetection fails) and by specifying the
> > > > QEMU binary via QEMU_TEST_QEMU_BINARY. For example:
> > > > 
> > > >    export PYTHONPATH=$HOME/qemu/python
> > > >    export QEMU_TEST_QEMU_BINARY=qemu-system-x86_64
> > > >    export QEMU_BUILD_ROOT=$HOME/qemu/build
> > > >    ~/qemu/tests/functional/test_virtio_version.py
> > > > 
> > > > The logs of the tests can be found in the build directory under
> > > > tests/functional/<arch>/<testname> - console log and general logs will
> > > > be put in separate files there.
> > > > 
> > > > Still to be done: Update the documentation for this new test framework.
> > > 
> > > I'll say again that the download *must* be handled separately from the test
> > > with timeout. This is an absolute show-stopper.
> > > 
> > > I've tried this twice now, from a decently fast connection in central
> > > Brisbane, and have had multiple downloads be canceled by the timeout.  Since
> > > the download isn't clever enough to pick up where it left off, it will never
> > > succeed.
> > 
> > This is a tricky problem the way the tests are currently written, given the
> > desire for a minimal-change from the old avocado impl.
> > 
> > IIUC, avocado already had a per-test timeout, so would suffer the same
> > problem with downloads exploding the "normal" running time when cached.
> 
> Avocado runs a first pass doing all of the downloads, and only afterward
> runs the actual timed tests.  I don't know the specifics of how, but it
> certainly obvious in the logging.

Oh interesting, I found how it does it..

The file avocado/plugins/assets.py will build an AST of the python
code in a test file, look for all 'fetch_asset' calls, then extract
the parameters to these calls, and donwload them. This is clever.
Basically avoids the refactoring that I suggested.

So yeah, that is a gap.

Practically speaking, we have a choice of either  calling into this
avocado python lib as is, or copying tthat python lib into QEMU.

With regards,
Daniel
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