bpo-44980: fix test_constructor to return None value

[akulakov]

Update test_constructor() to conform to deprecation in #27748

https://bugs.python.org/issue44980

[akulakov]

It might also be good to test contents of the null tuple?

[ambv]

You could but since we weren't looking at those before, this is new behavior that isn't necessarily the point of this PR.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @ambv for commit 0d986418e50ab4f029845fa115976a5837a0a450 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

[ambv]

"test-with-buildbots" will test for refleaks for us.

[serhiy-storchaka]

If tuple is NULL, the result should be NULL.

[akulakov]

I should wait for buildbots to finish to push this change right?

[serhiy-storchaka]

No, you do not need to wait for buildbots.

[akulakov]

Refleaks bot failure seems unrelated:

2:10:42 load avg: 5.18 [ 58/428/1] test_mailbox failed (1 failure) (2 hour 31 sec) -- running: test_gzip (1 hour 44 min), test_cmd_line (1 hour 39 min), test_argparse (1 hour 39 min)
beginning 6 repetitions
123456
..test test_mailbox failed -- Traceback (most recent call last):
File "D:\buildarea\pull_request.ware-win81-release.refleak\build\lib\test\test_mailbox.py", line 411, in test_set_item
self.assertEqual(len(self._box), 2)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 3 != 2

[serhiy-storchaka]

o1 and o2 may be leaked here.

[serhiy-storchaka]

No, you do not need to wait for buildbots.

[serhiy-storchaka]

Looking at the history of test_null_strings I decided that it should be completely rewritten. #27904.

[serhiy-storchaka]

BTW, comparing a pointer to freed memory with NULL is undefined behavior. Py_DECREF(tuple) should be after if (tuple == NULL).

[akulakov]

Looks like I've forgotten what I knew of C; thanks for reviewing and catching this!

[ambv]

I rebased on main.

[miss-islington]

Thanks @akulakov for the PR, and @ambv for merging it 🌮🎉.. I'm working now to backport this PR to: 3.9, 3.10.
🐍🍒⛏🤖

[bedevere-bot]

GH-27913 is a backport of this pull request to the 3.10 branch.

[bedevere-bot]

GH-27914 is a backport of this pull request to the 3.9 branch.

[akulakov]

I rebased on main.

@ambv thanks, I'll make sure to do that next time!