Tests are missing for IndexOutOfBoundsException. If you solve the problem with 11x11 matrix and receive an input with 6 steps in a row in a single direction, than you can hit index-out-of-bounds. This sort of valid, because any larger than that and the output would be FALSE - if you take 6 steps in one direction you cannot return with 4, but still I would add a test to make sure the solutions catch invalid inputs.