warning, getting a Counter while expecting a dict shouldn't raise. On the other hand, getting a dict while expecting a Counter should definitely raise.

It's not explicit in the description, but there is a test section that is very clear about the intent: @test.it("Handle inheritance correctly")

I didn't solve this kata, but:

>>>from collections import Counter
>>>type(Counter([]))
<class 'collections.Counter'>

In my understanding of the kata, it is not the same type (though it can be subclass).

Unless I misunderstood your post: do you mean the kata expects no exception in such cases? If so, I agreee the description is lacking some specifications.