If n is less than zero or more than or equal to the available strings, the function must return NULL.

"more than" ("zero\0one\0two\0\0many", 4) isn't tested: https://www.codewars.com/kata/reviews/66ca922c180b675e18865bb3/groups/66ce1f23bf5043bfb07639f1

While thinking about a better way to write it, I did the same thing accidentally. Well, it just shows a property of this sequence.

It doesn't seem clear from the description if the same value can appear in multiple layers.

The initial solution has function twoOldestAges.

if only some (but not all) the elements in the sequence are True

JavaScript:

Failed for 
seq : [  1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0,  0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1,  1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 0,  0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1,  0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1,  1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1]
pred : function parseInt() { [native code] }
reason : expected false to equal true

but parseInt never returns true...
Now trying truthy instead of true:

Failed for 
seq : Iterator [
  true,  true,  true,  true,  false, false, false, true,
  true,  false, false, false, false, false, true,  true,
  false, true,  false, false, true,  false, true,  false,
  false, false, true,  true,  false, true,  false, false,
  true,  true,  true,  false, false, false, true,  false,
  true,  false, true,  true,  true,  false, true,  false,
  false, false, true,  true,  false, false, false, true,
  false, true,  false, true,  true,  true,  true,  false,
  true,  false, true,  false, false, true,  false, true,
  true,  false, false, true,  true,  true,  true,  true,
  true
])
pred : function parseInt() { [native code] }
reason : expected false to equal true

but parseInt never returns a truthy value here...

IDK about edge case coverage, but out-of-bounds coordinates are still reported as "TypeError: result.forEach is not a function".

The random tests in Lua have multiple missing and repeated numbers.

Someone else approved the translation. I've done minimal fixing.
Missing tests with unsorted arrays, misssing random tests.

LLVM has troubles optimizing loops with inclusive upper bounds: https://github.com/rust-lang/rust/issues/45222

Technically, it does apply to this case, but this loop isn't vectorizable and my guess is that unrolling won't help with this division, so it doesn't really matter here.

The test expect a TypeError for bool, but bool is an integer type in Python.

The random tests capture the same mutable variable by reference.