bpo-37421: Fix test_distutils.test_build_ext()

[vstinner]

test_distutils.test_build_ext() is now able to remove the temporary
directory on Windows: don't import the newly built C extension ("xx")
in the current process, but test it in a separated process.

https://bugs.python.org/issue37421

[aeros]

@vstinner Thanks for changing the variable d to tmpdir on line 67 of support.py. In my opinion, non-descriptive variables can be the bane of readability.

Is there a particular reason or advantage in this case for wrapping the tests within a whitespace-stripped string instead of writing the Tests class within another file? I have no issues with it, I just haven't seen it done before.

[vstinner]

@vstinner Thanks for changing the variable d to tmpdir on line 67 of support.py. In my opinion, non-descriptive variables can be the bane of readability.

You're welcome.

Is there a particular reason or advantage in this case for wrapping the tests within a whitespace-stripped string instead of writing the Tests class within another file? I have no issues with it, I just haven't seen it done before.

It's more convenient to put everything at the same place. It's a very common pattern if you look at the Python test suite.

[miss-islington]

Thanks @vstinner for the PR 🌮🎉.. I'm working now to backport this PR to: 3.8.
🐍🍒⛏🤖

[bedevere-bot]

GH-14571 is a backport of this pull request to the 3.8 branch.

[aeros]

@vstinner Thanks for the explanation. I'm a newer contributor, so I'm not overly familiar with the common patterns within the Python test suite. However, I definitely am a fan of how compact it is, I'll definitely keep the format in mind. After finishing up reorganization of test_importlib, Brett had suggested that it'd be helpful to work on modernizing the tests over there. If possible, I'll use this format as a template.