Direct invocation of `test_inspect/test_inspect.py` fails

[sobolevn]

Bug report

» ./python.exe Lib/test/test_inspect/test_inspect.py
/Users/sobolev/Desktop/cpython2/Lib/test/test_inspect/test_inspect.py:43: ImportWarning: can't resolve package from __spec__ or __package__, falling back on __name__ and __path__
  from . import inspect_fodder as mod
Traceback (most recent call last):
  File "/Users/sobolev/Desktop/cpython2/Lib/test/test_inspect/test_inspect.py", line 43, in <module>
    from . import inspect_fodder as mod
ImportError: attempted relative import with no known parent package                                                         

I will send a PR.

Linked PRs

• gh-116785: Fix direct invocation of test_inspect #116787
• [3.12] gh-116785: Fix direct invocation of test_inspect (GH-116787) #116794
• [3.11] gh-116785: Fix direct invocation of test_inspect (GH-116787) #116795

[vstinner]

Should we really encourage usage of running directly tests?

Maybe it's time to give up on if __name__ == '__main__': ... and promote the new unittest CLI instead:

./python -m unittest Lib/test/test_inspect/test_inspect.py

But well, I'm fine with the fix.

cc @serhiy-storchaka

[sobolevn]

I find this really useful when you can click on a file in IDE and say "run this file". No build step, no settings, no nothing. It just works (until it does not 😄 ).

[serhiy-storchaka]

It was useful to make every toplevel test be runnable as a script. But it never worked well for tests in subdirectories and required too many inconvenient changes, so I gave up on this.