I think this kata isn't 4 kyu, maximum: 6 kyu or 7 kyu.

Feature Request: Edit submitted solution.

It's kind a strange that I can't edit submitted solution. Even if we have sometime for "refactor" before final submission - yeah, but nevertheless I made typo and want to fix it.

This isn't a good test assertion. To complete this test you need to define getter/setter on every instance (which is bad) instead of defining these getter/setter once on Cats.prototype.

So please change this test assertion to
Test.expect(Object.getOwnPropertyDescriptor(Cat.prototype, 'weight').get);

Hey @xcthulhu, first of all thanks for this kata, I can say that such task can be on ordinary commerical project — so it's definitely useful.
Nevertheless, I have no idea, why this particular solution was marked as "Best Practices" and "Clever" since monkey-patching any built-in prototype is considered as anti-pattern in JS dev.