functools.singledispatchmethod is missing tests (and is buggy in 3.9)

[AlexWaygood]

BPO	45678
Nosy	@rhettinger, @ambv, @miss-islington, @AlexWaygood
PRs	bpo-45678: Add functools.singledispatchmethod tests #29328 [3.10] bpo-45678: Add functools.singledispatchmethod tests (GH-29328) #29390 [3.9] bpo-45678: Add functools.singledispatchmethod tests (GH-29328) #29391 [3.9] bpo-45678: Fix singledispatchmethod classmethod/staticmethod bug #29394 bpo-45678: Add more singledispatchmethod tests #29412 [3.10] bpo-45678: Add more singledispatchmethod tests (GH-29412) #29424

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-11-05.15:28:00.977>
created_at = <Date 2021-10-30.12:10:31.370>
labels = ['type-bug', '3.9', '3.10', '3.11', 'library', 'tests']
title = '`functools.singledispatchmethod` is missing tests (and is buggy in 3.9)'
updated_at = <Date 2021-11-05.15:28:00.976>
user = 'https://github.com/AlexWaygood'

bugs.python.org fields:

activity = <Date 2021-11-05.15:28:00.976>
actor = 'lukasz.langa'
assignee = 'none'
closed = True
closed_date = <Date 2021-11-05.15:28:00.977>
closer = 'lukasz.langa'
components = ['Library (Lib)', 'Tests']
creation = <Date 2021-10-30.12:10:31.370>
creator = 'AlexWaygood'
dependencies = []
files = []
hgrepos = []
issue_num = 45678
keywords = ['patch']
message_count = 9.0
messages = ['405366', '405626', '405630', '405652', '405746', '405748', '405781', '405803', '405804']
nosy_count = 4.0
nosy_names = ['rhettinger', 'lukasz.langa', 'miss-islington', 'AlexWaygood']
pr_nums = ['29328', '29390', '29391', '29394', '29412', '29424']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue45678'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

[AlexWaygood]

test_functools includes a test to check that functools.singledispatch correctly wraps the attributes of the target function. However, there is no equivalent test for functools.singledispatchmethod. There should be, as this is done separately in the __get__ method of functools.singledispatchmethod; it is a different mechanism to functools.singledispatch.

Additionally, test_abstractmethod_register tests that the return value of singledispatchmethod.__get__ wraps the target function's __isabstractmethod__ attribute. However, the __isabstractmethod__ property of the singledispatchmethod class is untested.

[ambv]

New changeset 5a14929 by Alex Waygood in branch 'main':
bpo-45678: Add functools.singledispatchmethod tests (GH-29328)
5a14929

[ambv]

New changeset f191838 by Miss Islington (bot) in branch '3.10':
bpo-45678: Add functools.singledispatchmethod tests (GH-29328) (GH-29390)
f191838

[AlexWaygood]

Backporting these tests to 3.9 revealed a bug in the 3.9 branch; PR 29394 is an attempt at fixing this bug.

[ambv]

New changeset effb72f by Alex Waygood in branch '3.9':
[3.9] bpo-45678: Fix singledispatchmethod classmethod/staticmethod bug (GH-29394)
effb72f

[AlexWaygood]

Yet more tests were added to the 3.9 branch in PR 29394 in order to test the bugfix. PR 29412 "forward-ports" these new tests into main (and 3.10, if they are backported).

[ambv]

New changeset 32f55d1 by Alex Waygood in branch 'main':
bpo-45678: Add more singledispatchmethod tests (GH-29412)
32f55d1

[ambv]

New changeset bcb236c by Miss Islington (bot) in branch '3.10':
bpo-45678: Add more singledispatchmethod tests (GH-29412) (GH-29424)
bcb236c

[ambv]

Thanks, Alex! ✨ 🍰 ✨