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

[Daniel P . Berrangé]

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.

To address this we'll need a refactoring to enable us to declare the
required "assets" externally from the test code.

Taking one simple example

  class LinuxInitrd(QemuSystemTest):

      def test_with_2gib_file_should_exit_error_msg_with_linux_v3_6(self):

          kernel_url = 
('https://archives.fedoraproject.org/pub/archive/fedora/li'
                        
'nux/releases/18/Fedora/x86_64/os/images/pxeboot/vmlinuz')
          kernel_hash = '41464f68efe42b9991250bed86c7081d2ccdbb21'
          kernel_path = self.fetch_asset(kernel_url, asset_hash=kernel_hash)
          ...snip...

  if __name__ == '__main__':
      QemuSystemTest.main()


Consider if we declared all required assets as class level variable

  class LinuxInitrd(QemuSystemTest):

      ASSETS = {
         "fedora18": {
            "url": ('https://archives.fedoraproject.org/pub/archive/fedora/li'
                     'nux/releases/18/Fedora/x86_64/os/images/pxeboot/vmlinuz'),
            "hash": "'41464f68efe42b9991250bed86c7081d2ccdbb21'"
         }
      }

Then, we change the 'fetch_asset' method to take an asset name, not a
URL+hash:

      def test_with_2gib_file_should_exit_error_msg_with_linux_v3_6(self):
          kernel_path = self.fetch_asset("fedora18")

Now, 'fetch_asset' would lookup the URL + hash in the self.__class__.ASSETS
dict, so the test would run exactly as before.

Finally, we modify QemuSystemTest.main() so that knows to look for a
'--fetch-assets' parameter in sys.argv. When it see --fetch-assets,
instead of running each test, it should download everything found in
the ASSETS class variables.

This now gives us the ability to  run a separate '--fetch-assets'
invokation with elevated timeout, while runing tests with a normal
timeout.

This is all a non-trivial amount of work though, so I don't think
it is reasonable todo this as part of the immediate conversion in
this series.

The only short term option is to configure meson run tests with a
massively larger timeout, until we're able to enable some pre-caching
mechansim.

With regards,
Daniel
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