Kata

NodeJS version is too old (v8.1.3), it's recommended to upgrade it to v18, as well as testing framework to mocha/chai

For all who could stumble here on this old exercise, test don't check for true randomness. You HAVE to have at least one of each letter in result array.

The top voted solution is not random.

Each row starts with ['A','B','C','D',...]. I suggest adding a test like the one below, which catches the case where at least one column is all the same letter. This happens only 10 out of 4^9 = 262,144 times (0.004% odds) in a truly random array. So the vast majority of the random arrays should still pass with this new test in place.

function columnTest(res) { 
  for (var col = 0; col < 10; col++) 
    if (res.every(r=>r[col] == res[0][col])) 
      return false; 
  return true;
}

Doesnt seem so random if the first 4 elements are ABCD in all the arrays

Your babel presets doesn't contain String.prototype.repeat method. So I cannot pass tests with my solution :(

Approved

I'm confused run test is ok but submit have lots of error even the array length...

If you can't fix these issues below by yourself, I'd be happy to give you a hand! :)

Seems to be no test to enforce the randomness of the arrays.

more precise testing needed

There is a spelling/typo mistake in your problem outline...

Create 10x10 array and randomly WILL each cell with

I'm assuming WILL should be FILL

Should contain tests when the solution is called twiced and a test is made so that the solutions are not the same (to test randomness).

Please add more random tests to ensure all cells contains all needed letters.