test.py

def some_func():
  organization = Organization.objects.get(id=1)
  action_qs = organization.actions.filter(action='fund').by_month()
  return action_qs
  
def test():
  
  organization_mock = mocker.Mock()
  patch(..., organization_mock)
  
  # Monkeypatch organization_mock.actions with the new QuerySetMock
  members = [1, 2, 3]
  organization_mock.actions = QuerySetMock(members)
  
  actual = some_func()
  assert actual == organization_mock.actions.filter.by_month.return_value
  
  # test that the chained functions were called with the correct parameters
  expected = [
    Call('filter', name="one raft"), 
    Call('by_month')
  ]
  assert organization_mock.objects.filter.by_month.chain_called(expected)