gh-76273: Fix autospec mocking of instance and class methods

[stephenfin]

Currently, when patching instance / class methods with autospec, their self / cls arguments are not consumed, causing call asserts to fail (they expect an instance / class reference as the first argument).
Example:

from unittest import mock

class Something(object):
    def foo(self, a, b, c, d):
        pass

with mock.patch.object(Something, 'foo', autospec=True):
    s = Something()
    s.foo()

Fix this by skipping the first argument when presented with a method.

Based on #4476 with the changes to the Mock signature stripped out and left for a separate, follow-up PR.

• Issue: mock.patch with autospec does not consume self / cls argument #76273

[johnslavik]

Hi! Nice to see some work on this. Btw, we generally avoid force pushes.

[stephenfin]

Btw, we generally avoid force pushes.

Understood. I've got a small bit more work to do this on to resolve the test_hmac_constructor_uses_builtin failure (we need to handle calling patch.object(cls, name, autospec=True, wraps=wraps) where wraps is unbound). If I push a patch will it be squashed on merge? I can't see anything in the contributor docs in relation to this.

[johnslavik]

If I push a patch will it be squashed on merge?

Yes, all PRs are squashed on merge.

I can't see anything in the contributor docs in relation to this.

I see! It's in https://devguide.python.org/getting-started/pull-request-lifecycle/#don-t-force-push. Maybe we can make it more visible elsewhere, what do you think? Let me know what you had read before you created the PR, maybe we can add it there :-) Thanks for saying that you didn't see that note.