Confirming that the "Draw" cases appear to have been corrected! Hooray!!! (And, thanks!)

(Also, the example above was missing a check for SE to NW diags. Which has also been corrected.)

Second that ^

7 fail for me. All of the following format:

Expected: 'Yellow', instead got: 'Draw'

My code correctly predicts "Draw" but, in all 7 cases, one of the two players is expected (incorrectly.)

[ [ '', '', '', '', '', '', 'R' ],
[ '', 'Y', '', 'R', 'R', '', 'Y' ],
[ '', 'Y', '', 'Y', 'R', '', 'Y' ],
[ 'R', 'R', '_', 'R', 'Y', 'R', 'Y' ],
[ 'R', 'R', 'Y', 'Y', 'R', 'Y', 'R' ],
[ 'Y', 'Y', 'R', 'R', 'Y', 'R', 'Y' ] ]

Sorry about the formatting - doesn't render correctly in the comments here but if you copy it into a markdown reader it'll show the last game state.

Nit: the test cases pass in ints not strings. This precludes some very large numbers from being used as arguments (especially in JS which has a lower highest int)!

  test(0,5);
  test(4,5);
  test(10,2);
  test(20,3);
  test(60,5);
  test(219,11);
  test(729,9)
  test(1000,10);
  test(600001,100);