unittest.mock.patch with autospec doesn't hold for classmethods nor staticmethods

[rileyjohngibbs]

Bug report

Using patch with autospec=True does not work when a method is decorated with @classmethod or @staticmethod. The resulting mock can be called with any arguments without raising a TypeError.

Example:

from unittest.mock import patch
import pytest

class Foo:
    def foo(self):
        pass
    @staticmethod
    def bar():
        pass
    @classmethod
    def baz(cls):
        pass

@pytest.mark.parametrize("method", ["foo", "bar", "baz"])
def test_foo(method: str):
    with patch.object(Foo, method, autospec=True):
        getattr(Foo(), method)(5)

The only subtest that fails is foo. The other two pass, even though they're clearly being called incorrectly.

If you prefer not to use pytest to demo/repro this:

with patch.object(Foo, "foo", autospec=True):
    try:
        Foo().foo(5)
    except TypeError:
        print("Correctly raises on foo")
    else:
        print("Incorrectly does not raise with foo")

with patch.object(Foo, "bar", autospec=True):
    try:
        Foo().bar(5)
    except TypeError:
        print("Correctly raises on bar")
    else:
        print("Incorrectly does not raise with bar")

with patch.object(Foo, "baz", autospec=True):
    try:
        Foo().baz(5)
    except TypeError:
        print("Correctly raises on baz")
    else:
        print("Incorrectly does not raise with baz")

This has output:

Correctly raises on foo
Incorrectly does not raise with bar
Incorrectly does not raise with baz

Your environment

• CPython versions tested on: 3.10, 3.11
• Operating system and architecture: macOS 12.6 with Apple M1 chip

Linked PRs

• gh-102978: Fix mock.patch function signatures for class and staticmethod decorators #103228
• [3.11] gh-102978: Fix mock.patch function signatures for class and staticmethod decorators (GH-103228) #103499

[tomasr8]

Looks like the signature is not set for @classmethod and @staticmethod. Adding a special case for them and using __func__ to get the correct signature I was able to get it to work. I'll see if I can contribute a PR that fixes this.

[arhadthedev]

@cjw296 Can this issue be considered completed? The child PR gh-103228 is neither merged nor backported yet.