Bug report

3.12.0a7 changed the behavior of unittest.mock.PropertyMock

Setup:

from unittest.mock import MagicMock, PropertyMock
m = MagicMock()
p1 = PropertyMock(return_value=3)
p2 = PropertyMock(side_effect=ValueError)
type(m).foo = p1
type(m).bar = p2

In Python 3.12.0a6 and earlier, m.foo evaluates as 3, and m.bar raises a ValueError.

In Python 3.12.0a7, m.foo evaluates as 3, and m.bar returns <MagicMock name='mock.bar' id=...>

Your environment

• CPython versions tested on: 3.12.0a7, 3.12.0a6, 3.11.2, 3.10.10, 3.9.16, 3.8.16
• Operating system and architecture:
  • macOS Ventura 13.2.1, on an M1 MacBook Pro.
  • GitHub Actions macOS 12 x86_64
  • GitHub Actions Ubuntu 22.04
  • GitHub Actions Windows Server 2022

Linked PRs

• gh-103329: Add regression test for PropertyMock with side effect #103358
• [3.11] gh-103329: Add regression test for PropertyMock with side effect (GH-103358) #103364