[RFC PATCH v2 0/7] tests: run python tests under a venv

[John Snow <jsnow@redhat.com>]

Hi, here's another RFC for bringing external Python dependencies to the
QEMU test suite.

This patchset is not without some problems that need to be solved, but
I've been sitting on these long enough and they need to see the light of
day.

Problems I am aware of, and there's a few:

- Ubuntu 18.04 ships with a version of pip that is too old to support
  setup.cfg-based installations. We are allowed to drop support for
  18.04 by now, but we need a suitable 32bit debian VM configuration to
  replace it.

- Multiple VM tests are still failing for me; but they fail with or
  without my patches as far as I can tell. I'm having problems with
  Haiku and CentOS, primarily -- which I think fail even without my
  patches. I'll have more info after the weekend, these tests are SLOW.

- This version of the patch series does not itself enforce any
  offline-only behavior for venv creation, but downstreams can modify
  any call to 'mkvenv' to pass '--offline'. A more flexible approach
  might be to allow an environment variable to be passed that toggles
  the switch on.

- iotests will now actually never run mypy or pylint tests by default
  anymore, because the bootstrapper won't select those packages by
  default, and the virtual environment won't utilize the system packages
  -- so iotest 297 will just "skip" all of the time now.

  The reason we don't want to install these packages by default is
  because we don't want to add dependencies on mypy and pylint for
  downstream builds.

  With these patches, 297 would still work if you manually opened up the
  testing venv and installed suitable mypy/pylint packages there. I
  could also add a new optional dependency group, and one could
  theoretically invoke a once-per-build-dir command of 'make
  check-venv-pylint' to help make the process only semi-manual, but it's
  still annoying.

  Ideally, the python checks in qemu.git/python/ can handle the same
  tests as 297 does -- but we need to give a shorthand invocation like
  "make check-python" that is excluded from the default "make check" to
  allow block developers to quickly opt-in to the same tests.

  I've covered some of the problems here on-list before:
  https://lists.gnu.org/archive/html/qemu-devel/2022-05/msg03661.html

  ...But I haven't quite solved them yet.

That's all for now.

Paolo, can we chat about build system integration next? I want to know
how you envision the integration at this point -- adding different
test-invocation styles (online, offline, etc) may help solve the iotest
297 problem and the iotest self-bootstrap problem.

--js

John Snow (7):
  tests: create optional tests/venv dependency groups
  tests: pythonize test venv creation
  tests: Remove spurious pip warnings on Ubuntu20.04
  tests/vm: add venv pre-requisites to VM building recipes
  tests: add 'check-venv' as a dependency of 'make check'
  iotests: use tests/venv for running tests
  iotests: self-bootstrap testing venv

 tests/Makefile.include        |  32 +++---
 tests/mkvenv.py               | 187 ++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/testenv.py |  25 +++--
 tests/requirements.txt        |   6 --
 tests/setup.cfg               |  20 ++++
 tests/setup.py                |  16 +++
 tests/vm/netbsd               |   1 +
 tests/vm/ubuntu.i386          |   9 +-
 8 files changed, 268 insertions(+), 28 deletions(-)
 create mode 100644 tests/mkvenv.py
 delete mode 100644 tests/requirements.txt
 create mode 100644 tests/setup.cfg
 create mode 100644 tests/setup.py

-- 
2.34.3