Yes, I see that too.

Oh, I got it, results were flipped.
Great, thanks. Works well for me too.

Hey, something is seriously wrong with random tests
I get things like
Expected: '0.001179999999999999810^3', instead got: '1.18'
or
Expected: '1500000000000000210^-17', instead got: '1.5*10^-1'

Why? :-)

Cool Kata.
However, it's all but natural to use getFullYear() now and been like this for 16 years.
"year 2000 problem" is a surprise to meet here. Good for eductional purposes, but not actual at the moment at all. I think tests on this problem should be removed.

The format of the output is unclear. Just write an example as a string that would match with any expected result.
For example "'s" appended to a username is something you can only guess from an error

I've noticed a problem with ECMAScript2016 declaration. It wouldn't accept
const max = () => {}
only
function max() {}
Plus, the last of the test asserts has an open square bracket and it causes errors

I would recommend denoting this to 7 kyu.
Just solved a couple of 8 kyus that were much harder.