Clever doesn't necessarily mean best practices. I once saw a solution that was worded in the longest way possible (like, absurdly long) and it got clever because most people got a laugh out of it, lol.

Your solution is quite a bit slower than this one actually ;)

Benchmarking on the same input, this solution provides:

Ops/s: 5,122,611

Yours is:

Ops/s: 740,402

While this behaviour is indeed an artifact of the testing system, it is also so easily accidentally stumbled upon that I would still consider the kata to be broken. It is also very easily fixed by moving the describe and it block from preloaded to the the sample and full tests. ( Fork here which fixes it )

Yea, this kata is quite broken...

Not a kata issue. Closing.

Don't add additional letters or blank lines of code. You were warned that "the size of your solution is limited."

Closing.

Except C++!

It's not an algorithm, but it's still programming, sure. This teaches you the dangers of using vanilla to_lower/to_upper methods. This is something that comes back to bite a lot.

Oops, JavaScript.

Not sure why this is getting "clever" votes... This is a very verbose way to do this...

Specify the language where it is broken.

This kata is language-agnostic. The solution string behaves the same in all programming languages.