Is there a way to assert that an attribute has been set on a unittest mock object?

In the following code, is there a way to assert that the query attribute has been set if search is a mock object? Or if query was the mock object, is there a way to do it?

search.query = Q('bool', must=must)

So far I've found out that Python unittest.mock only supports asserting that mocks have been called as functions. Also the setattr magic method can not be mocked so search.__setattr__ can not be used to assert the above.