Test-Driven Java Development - Second Edition

Test – winning condition IV

Finally, there is the last possible winning condition to tackle:

@Test
public void whenPlayAndBottomTopDiagonalLineThenWinner() {
  ticTacToe.play(1, 3); // X
  ticTacToe.play(1, 1); // O
  ticTacToe.play(2, 2); // X
  ticTacToe.play(1, 2); // O
  String actual = ticTacToe.play(3, 1); // X
  assertEquals("X is the winner", actual);
}

The player wins when the whole diagonal line from the bottom-left to top-right is occupied by his pieces.