Thank you for the kind words. Take a look at the answer by @mikgra also... it's very good. The anchors are necessary according to the problem description. Without the anchors, a length of "xyz123" would create a zero-length array rather than raising an error. If the kata's tests pass without the anchors, then I would think there must be missing tests.

I would agree. In the instructions, you state that a passing case is "WeIrD StRiNg CaSe" which counts spaces when capitalizing even indices. However, your test case seems to ignore spaces as counting as even indices.

I'm getting this as well... And no I'm not actually calculating factorials. Figure it out?

I think your comment has a little problem too ;). What's the problem in the kata? Also check whether the problem has already been covered by other users.