[RFC PATCH v3 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 is mostly a refresh of a version I sent out before, but mixes in my
VM improvement test as an optional pre-requisite to improve VM test
stability to ensure that the BSDs all pass with the new
infrastructure. (And our oldest supported Debian and Ubuntu targets,
too.)

(Note: this requires dropping support for Ubuntu 18.04, which ships with
a version of setuptools that is simply too old.)

This patchset is still not without some problems that I am working on,
but progress has been slow.

Problems I am aware of:

- 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'. I am working on a configure
  file toggle to swap the default behavior when running tests.

- 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-iotests' 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.

- iotests can now self-bootstrap the venv when it isn't present, but
  this self-bootstrapping has some issues in that because it skips the
  Makefile magic, it cannot update the venv when changes are made to the
  venv configuration piece.

That's all for now. Work on the configure file integration is ongoing. I
don't know if I'll beat soft freeze (It's looking unlikely given the
amount of IRL issues I am juggling right now), but I'm hoping to push as
much of this forward as I can to try and get some testing in for RC
phase to determine what problems might exist that I haven't noticed yet.

--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 +
 7 files changed, 262 insertions(+), 25 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