Thanks, I've updated the test cases to cover undefined values in the input array.

No, uniq(['a','a','b','b','c','a','b','c','c']) should return ['a','b','c','a','b','c'].
uniq only reduces consecutive duplicate entries (see also: https://en.wikipedia.org/wiki/Uniq).

Thanks for pointing out this flaw in the test case. I've added a length verification and some more tests to test various aspects of the uniq() behaviour.

Yes, this fits more with the theme of the kata. I've updated the kata. Thanks!