Mock spec not respected for attributes prefixed with assert

[cklein]

Bug report

Example:

from unittest.mock import Mock
class Foo:
    def assert_something(self):
         pass

m = Mock(spec=Foo)
m.assert_something()

An exception is raised:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/cklein/github/cklein/cpython/Lib/unittest/mock.py", line 657, in __getattr__
    raise AttributeError(
AttributeError: 'assert_something' is not a valid assertion. Use a spec for the mock if 'assert_something' is meant to be an attribute.

Python 3.9 and lower:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/unittest/mock.py", line 635, in __getattr__
    raise AttributeError("Attributes cannot start with 'assert' "
AttributeError: Attributes cannot start with 'assert' or 'assret'

The error message suggests that accessing attributes with prefix "assert_" should work when using a spec.

See cklein@735ffc4 for a possible fix

Your environment

• CPython versions tested on:
• 3.12.0a3+
• 3.11.1
• 3.10.9
• 3.9.16
• 3.8.16
• 3.7.16
• Operating system and architecture:
  • Darwin 21.6.0 on arm64
  • Linux 5.4.0-1088-aws on x86_64 (only Python 3.7.5 and 3.8.0)

Linked PRs

• gh-100739: Respect mock spec when checking for unsafe prefixes #100740
• [3.11] gh-100739: Respect mock spec when checking for unsafe prefixes (GH-100740) #100760
• [3.10] gh-100739: Respect mock spec when checking for unsafe prefixes (GH-100740) #100761

[AlexWaygood]

Fixed, and backported to 3.11 and 3.10. Thanks @cklein!