I believe the tests are comparing the valueOf Card objects.
(I don't feel bad revealing this information because it should really be given with the kata, but feel free to mark as a spoiler.)

I am stuck on the same tests as well. I understand the concept of a Comparable mixin but implementing one in JavaScript can go many ways without knowing the expected interface or test expectations. Please provide some more details or expectations for the JS version?

I'm stuck at the same tests and I have no idea how to solve this. Any tips?

The tests require cards to be somehow returned to the deck. This feature is unmentioned in the description, and there's no way to determine under what conditions the cards are supposed to be returned. Is there some method that's supposed to handle that?

Could you elaborate on what it means to be Comparable? There is no information on what elements are being compared, or what the expected output is. The tests that fail because of this give no useful information, unfortunately.

Did you change your code, or did the method mysteriously start working? I'm still getting NoMethodErrors for Array#any? and Array#all?

I think eql? returns true only if the two arrays contain the same content. We're supposed to be checking if the numbers in the passed in array are seen in the current array. So a passed in array of [1,2,3] should return true for a current array of [0,1,3,4,2], since 1,2 and 3 are commmon to both arrays. However, both arrays do not have the same content.