bpo-5846: Deprecate obsolete methods in unittest

[erlend-aasland]

• unittest.findTestCases
• unittest.makeSuite
• unittest.getTestCaseNames

Scheduled for removal in Python 3.13

https://bugs.python.org/issue5846

[erlend-aasland]

Replaces GH-20400.

[serhiy-storchaka]

I am working on a patch which gets rid of uses of obsolete functions.

[erlend-aasland]

I had to adapt test_support, since __module__ is now unittest instead of unittest.loader for these three functions.

[serhiy-storchaka]

Are all tests warning-free?

If these functions are not used in unittest tests, add special tests, catch DeprecationWarning and check the filename attribute (to ensure that the stacklevel is correct).

[serhiy-storchaka]

Why not add deprecations when they are defined?

[erlend-aasland]

IIUC, it is the "shortcuts" that are deprecated, not the methods themselves. Should I deprecate the undocumented unittest.TestLoader.makeSuite and unittest.TestLoader.findTestCases as well?

[serhiy-storchaka]

There are no unittest.TestLoader.makeSuite and unittest.TestLoader.findTestCases.

[erlend-aasland]

Sorry, I meant unittest.loader, not unittest.TestLoader:

>>> import unittest
>>> unittest.loader.makeSuite
<function makeSuite at 0x10be0e2a0>
>>> unittest.loader.findTestCases
<function findTestCases at 0x10be0e340>
>>> 

[erlend-aasland]

Thanks for reviewing and merging, @serhiy-storchaka and @ambv!