PR: Catch leaks in the test suite

[impact27]

Description of Changes

• Wrote at least one-line docstrings (for any new functions)
• Added unit test(s) covering the changes (if testable)

• Included a screenshot or animation (if affecting the UI, see Licecap)

Issue(s) Resolved

Fixes #17213

Affirmation

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I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

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[pep8speaks]

Hello @impact27! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file spyder/app/tests/test_mainwindow.py:

Line 369:80: E501 line too long (82 > 79 characters)

Comment last updated at 2022-01-21 16:41:32 UTC

[ccordoba12]

@impact27, could you describe what you're trying to achieve here? Also, where exactly are you fixing issue #17213 in this PR? Sorry, but I can't easily spot that.

[impact27]

The goal here is to check that no file or process is opened in a test and not closed. While working on this I noticed #17213. This bug is caused by closing the stdout and stderr file without stopping the restarter. The restarter therefore tries to restart the kernel, but can’t access the files, as they are closed.

[ccordoba12]

Thanks @impact27 for your help with this! It looks almost ready to me, with the exception of one test you changed to make it pass (which I think is incorrect).

[ccordoba12]

Looks good to me now, thanks @impact27!