Python unittest.patch - patching a class attribute to return different results each time the attribute is accessed

Question

I need to patch/mock a class instance attribute so that each time it is called it returns a different value. The class instance attribute is a managed list which can change every time its accessed due to other processes adding to it.

I believe I should be able to use patch and the side_effect option to return different values per call but this does not seem to work with attributes as they are not called. I have tried various versions of patch and tried providing different callable (new_callable=) such as PropertyMock and other custom functions but I cant seem to get the desired behaviour. Can anyone suggest what I should do or what I'm doing wrong?

Basic example code and test shown below.

Code under test

# klass.py

import multiprocessing as mp
from unittest.mock import patch

class Klass:

    def __init__(self):
        self.manager = mp.Manager()
        self.finished_item_ids = self.manager.list()
        
    def func(self, item_id):
        return item_id in self.finished_item_ids

And the pytest test

# tests_klass.py
"""pytest test for Klass.func"""

from unittest.mock import patch

def test_Klass_func():
    """test Klass.func"""
    
    # SETUP
    k = Klass()
    
    # TEST
    with patch.object(k, "finished_item_ids", side_effect=[[101], [101, 102], [101, 102, 103]]):
        assert k.func(101) is True
        assert k.func(102) is True
        assert k.func(103) is True

Thanks :)