# test.py

import module
from unittest import mock

def test_a():
  def thing_side_effect(self):
    pass

  with mock.patch('module.class_.thing', new=mock.PropertyMock(side_effect=thing_side_effect, autospec=True)):
    module.class_().thing()

# module.py

class class_:
  @property
  def thing(self):
    return

# test.py

import module
from unittest import mock
import pytest

def test_a():
  def thing_side_effect(self):
    pass

  with mock.patch('module.class_.thing', side_effect=thing_side_effect, autospec=True):
    module.class_().thing()

# module.py

class class_:
  def thing(self):
    return