We can test the draw result by filling all the board's boxes:
@Test public void whenAllBoxesAreFilledThenDraw() { ticTacToe.play(1, 1); ticTacToe.play(1, 2); ticTacToe.play(1, 3); ticTacToe.play(2, 1); ticTacToe.play(2, 3); ticTacToe.play(2, 2); ticTacToe.play(3, 1); ticTacToe.play(3, 3); String actual = ticTacToe.play(3, 2); assertEquals("The result is draw", actual); }