Test Python 3.10 support

[pradyunsg]

We're still gonna be on the legacy branch of virtualenv, but hopefully this helps us move forward soon.

[pradyunsg]

/cc @hugovk, since they had looked into this earlier?

[pradyunsg]

Ok, cool. So, our tests can be run like this. Now, who wants to actually fix the two failures? :)

[puetzk]

test_pip_works_with_warnings_as_errors just seems to be assertion errors on the distutils deprecation from within packaging.tags, which should be fixed by #10144

I'm not sure what's going on in test_correct_pip_version, obviously the regex didn't match, but it didn't capture what pip --version did print.

[puetzk]

Oh duh, the regex at

pip/tests/lib/test_lib.py

Line 48 in 3301426

r"\(python \d(.[\d])+\)$",

doesn't allow for two-digit version numbers (needs to be [\d]+)

[puetzk]

I guess in the past python only got to 1.6 and 2.7, so 3.10 it's the first time that's ever happened in the major or minor :-)

[pradyunsg]

Okay, those seem easy and my Internet provider has restored the connection now.

[hugovk]

Pinning 3.10.0-beta.4 in GitHub Actions is the safest option, but 3.10-dev should track the 1-2 RC releases too.

And the beta should be pretty stable, and if not, we probably want to know about it sooner to report upstream.

[hugovk]

Oh duh, the regex at

pip/tests/lib/test_lib.py

Line 48 in 3301426

r"\(python \d(.[\d])+\)$",

doesn't allow for two-digit version numbers (needs to be [\d]+)

Tip: run https://github.com/asottile/flake8-2020 to find other possible problems introduced by the first-ever two-digit minor version. I think pip is good, worth a quick check again.

[uranusjr]

IIRC someone already did that on the main code base a while ago, back when 3.10 was first confirmed to going to happen.

[pradyunsg]

IIRC Anthony did that for pip when he wrote flake8-2020.

[pradyunsg]

x-ref #8273 since that is still the main annoying part.

[puetzk]

deleted (meant to comment on the relevant line)

[uranusjr]

Maybe we could do --use-venv on Python 3.10 and get it in first for most stuff; IIRC only ~1% of the tests are currently incompatible with venv.

[pradyunsg]

The problem isn't virtualenv -- there's only one failure test_pip_works_with_warnings_as_errors; and that's happening because we're importing distutils which has a warning on import now.

[pfmoore]

there's only one failure test_pip_works_with_warnings_as_errors

Hmm, how is ensurepip in cpython core passing the 3.10 test suite in that case? That test was, I believe, specifically added because the CPython test suite runs with warnings as errors...

[pradyunsg]

Hmm, how is ensurepip in cpython core passing the 3.10 test suite in that case?

🤷

Well, I think I wanna skip it for this initial round of adding 3.10 testing -- if this is indeed a problem for CPython, we'd catch it there. If not, well, the users who see this on 3.10 can adapt -- they're doing a migration/upgrade already.

[uranusjr]

Hmm, how is ensurepip in cpython core passing the 3.10 test suite in that case?

I don’t know why, but apparently pip install a wheel on 3.10 does not trigger any distutils warnings:

$ virtualenv --python python3.10 --no-pip ./x
...

$ ./x/bin/python -c 'import distutils'  # Triggers a warning as expected
<string>:1: DeprecationWarning: The distutils package is deprecated and slated for removal in Python 3.12. Use setuptools or check PEP 632 for potential alternatives

$ ./x/bin/python -m ensurepip  # No warnings!
Looking in links: /tmp/tmpymqbilj5
Requirement already satisfied: setuptools in ./x/lib/python3.10/site-packages (57.0.0)
Processing /tmp/tmpymqbilj5/pip-21.1.3-py3-none-any.whl
Installing collected packages: pip
Successfully installed pip-21.1.3

$ ./x/bin/python -m pip install -U pip  # Also no warnings!
Requirement already satisfied: pip in ./x/lib/python3.10/site-packages (21.1.3)
Collecting pip
  Using cached pip-21.2.3-py3-none-any.whl (1.6 MB)
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 21.1.3
    Uninstalling pip-21.1.3:
      Successfully uninstalled pip-21.1.3
Successfully installed pip-21.2.3

[uranusjr]

I think this needs to be fixed #10164 (comment)

[pfmoore]

I don’t know why, but apparently pip install a wheel on 3.10 does not trigger any distutils warnings

https://github.com/python/cpython/blob/main/Lib/ensurepip/__init__.py#L92

[pfmoore]

This test was only added because the CPython test suite failed when packaging raised a deprecation warning (for legacy versions, IIRC). As ensurepip now forcibly silences deprecation warnings as part of the distutils removal, we could probably just drop this (after all, I don't think we should guarantee that pip runs warning-free as a general matter).

But it's no big deal either way.

[pradyunsg]

Gonna remove in a follow up. :)

[puetzk]

version regex looks good to me now.