Simplify the logic run for pytest version inside the venv

[j-rivero]

Mostly inspired by this comment of @dirk-thomas #498 (comment). Should help to ix the regressions found in #498.

Implementation: print the pytest version inside the venv using job.run and move the version check logic outside of the venv.

Tested with ament_package on Foxy in:

• Linux
• Linux-aarch64
• macOS
• Windows

[dirk-thomas]

This line is unnecessary.

[j-rivero]

if we define the variable only inside the with clause, could it be used outside of that scope?

[dirk-thomas]

Yes.

[j-rivero]

Please do not merge, using foxy ros2 repos file is failing:

• Linux

Looking into this now.

[j-rivero]

This is confusing me: the test display to be using pytest-6.0.1, I've verified that this information is being generated fine in this PR and goes to the temporary file. Some lines after this message appear PytestDeprecationWarning: The 'junit_family' default value will change to 'xunit2' in pytest 6.0. See: like if it was not using pytest6. Or do I am missing something obvious?

�[1m============================= test session starts ==============================�[0m
platform linux -- Python 3.8.2, pytest-6.0.1, py-1.9.0, pluggy-0.13.1
cachedir: /home/jenkins-agent/workspace/ci_linux/ws/build/ament_package/.pytest_cache
rootdir: /home/jenkins-agent/workspace/ci_linux/ws/src/ament/ament_package, configfile: pytest.ini
plugins: colcon-core-0.6.0, mock-3.2.0, repeat-0.8.0, rerunfailures-9.0, cov-2.10.0
�[1mcollecting ... �[0m�[1m
collected 1 item                                                               �[0m

test/test_flake8.py �[32m.�[0m�[33m                                                    [100%]�[0m

�[33m=============================== warnings summary ===============================�[0m
/home/jenkins-agent/workspace/ci_linux/venv/lib/python3.8/site-packages/_pytest/junitxml.py:446
  /home/jenkins-agent/workspace/ci_linux/venv/lib/python3.8/site-packages/_pytest/junitxml.py:446: PytestDeprecationWarning: The 'junit_family' default value will change to 'xunit2' in pytest 6.0. See:
    https://docs.pytest.org/en/stable/deprecations.html#junit-family-default-value-change-to-xunit2
  for more information.
    _issue_warning_captured(deprecated.JUNIT_XML_DEFAULT_FAMILY, config.hook, 2)

[j-rivero]

Or do I am missing something obvious?

Don't have more time to investigate what's going on with the pytest enviroment, an alternative to these changes that seems not to fix the problem is pr #502

[jacobperron]

It does seem odd. Locally, I can reproduce the test warning with pytest 6.0.1 building ament_package foxy branch.
Maybe we need to make the patch to the pytest.ini regardless?

[jacobperron]

After some reading and experimentation, I think we should expect the deprecation warnings to appear if junit_family is not explicitly set (in the pytest.ini or otherwise).

The problem here is that we're assuming if junit_family is set to "legacy", then we don't have to patch the pytest.ini file; however, we'll still get a deprecation warning if it is not set at all.

Unless there's some reason we shouldn't always set junit_unit=xunit2 for Dashing, Eloquent, and Foxy, I think something like #502 is a cleaner solution. Furthermore, I don't think we need to patch the pytest.ini file, and can instead set junit_family from the command-line (see c6b5dc7)