While I agree having more tests are a good thing, I'm not sure if the test in PR 11437 should be merged as it's not specifically testing a feature of the mock module.

patch.dict() basically does the following operation (ignoring possible AttributeErrors):

   # Keep the original one to use later.
   d = original_dict.copy()

   original_dict.update(new_dict)

I think the relationship between dict and OrderedDict (including any other dict subclasses and dict-like objects) and anything related to insertion order should be tested either in test_dict or in test_ordered_dict.

Also, the test can be simplified, but I will let other core developers chime in with their thoughts before reviewing PR 11437 on GitHub.