Move all stdlib tests in the test package

[vstinner]

Currently, Python tests are scattered in multiple directories:

• Lib/test/ (main one)
• Lib/ctypes/test/
• Lib/distutils/tests/
• Lib/idlelib/idle_test/
• Lib/lib2to3/tests/
• Lib/tkinter/test/
• Lib/unittest/test/

idlelib, ctypes, lib2to3, tkinter, unittest and distutils have their tests under their own packages. It causes multiple issues:

• As a maintainer of Python, I have to look into these directories manually when refactoring "Python tests" (I cannot just look into Lib/test/).
• Linux distributions have to manually put these directories into a separated packages if they want to make the main "python" package smaller, to put python tests into a separated package.
• Makefile is more complicated since tests are installed separately, and so these directories should be listed explicitly in the TESTSUBDIRS variable.
• Tools/scripts/generate_stdlib_module_names.py excludes manually these modules, since sys.stdlib_module_names excludes test modules.

I propose to move ctypes, idlelib, tkinter and unittest tests under Lib/test/.

For distutils and lib2to3, maybe we can just leave them where they are, since both modules are deprecated. distutils should be removed in Python 3.12. lib2to3 is scheduled for removal in Python 3.13.

Do you think that it's worth it to move these directories?

[vstinner]

It seems like the Windows installer only treat Lib/test/ separately: see Tools/msi/test/test.wixproj. I would be nice to also exclude the other test directories to make Python installation smaller on Windows.

$ du -sh ctypes/test/ distutils/tests/ idlelib/idle_test/ lib2to3/tests/ tkinter/test/ unittest/test/
348K	ctypes/test/
336K	distutils/tests/
624K	idlelib/idle_test/
440K	lib2to3/tests/
284K	tkinter/test/
700K	unittest/test/

The total is about 2 732 KB.

On Fedora 36, the Python 3.10 tests (python3-test package) take around 54 MB in total (it includes idle_test, ctypes tests, etc.).

$ sudo dnf install python3-test
(...)
Total download size: 9.7 M
Installed size: 54 M

[rhettinger]

Do you think that it's worth it to move these directories?

Yes, yes, yes!

[zware]

This appears to duplicate #54781.

I'm still in favor :)

[vstinner]

I started with:

• ctypes: PR gh-93839: Move Lib/ctypes/test/ to Lib/test/test_ctypes/ #94041
• unittest: PR gh-93839: Move Lib/unttest/test/ to Lib/test/test_unittest/ #94043

[terryjreedy]

Please leave idlelib/idle_test alone. Following gives some of reasons:
#54781 (comment)
There are also several references to files in this directory in idlelib and idlelib.test_idle files.

[merwok]

Could you exclude idle and distutils from your list, and attach the new PRs to the other ticket?

[vstinner]

I merged my ctypes and unittest PRs. Ok, let's continue in issue #54781.

[tiran]

PR #94043 broke testing on all WebAssembly platforms.

[vstinner]

PR #94043 broke testing on all WebAssembly platforms.

Please comment #54781. This issue is a duplicate.