Yes, the random tests are vulnerable to input modification. No, if you do not modify the input the tests are not wrong. Yes, if you modify the input you deserve whatever you get.

Note that [].sort modifies its input.

Not a kata issue. Closing.

Same error without modifying the input in JS :

[ 19, 72, 16, 50, 25, 92, 80, 23, 40, 63, 26, 99, 42, 18, 68, 3, 75, 96 ]

Expected: '[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18]', instead got: '[15, 6, 17, 9, 13, 3, 4, 14, 11, 8, 12, 1, 10, 16, 7, 18, 5, 2]'

What about 'cheese&beer'?

Javascript

What language is failing? I'll look into why it is doing so now.

do you mutate the input?

I think the tests may be wrong. When the test is the following:
[ 16, 83, 3, 69, 31, 27, 73, 49, 9, 99, 93, 22, 70, 32, 98, 29, 36, 6, 38 ]

I get the following result:
Expected: '[19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1]', instead got: '[16, 4, 19, 7, 12, 14, 5, 8, 17, 1, 3, 15, 6, 11, 2, 13, 10, 18, 9]'

What language are you using? I just realized there are not 900 tests in python (just some...). Unfortunately, I won't be capable of helping you in PHP or JS, sorry.

So is this something on the kata's side? I pass over 900 tests before it just stops, and none of the 900+ tests failed. It just sort of times out and prints that error.

I'd bet that if you fail some tests, with inputs as big as they are, the assertion message will cause the very same problem than if you were actually printing something to the console yourself.

I'm having the same issue. It passed all 900+ tests, but I'm getting the following error even though I didn't write anything to STDOUT:
Max Buffer reached: Too much information has been written to stdout.

I didn't write any output to STDOUT, yet I'm getting the following error:

Max Buffer reached: Too much information has been written to stdout.