assertEquals(Board.NONE, game.board.get(0, 0));
assertEquals(Board.NONE, game.board.get(1, 1));
assertEquals(Board.NONE, game.board.get(2, 2));
game.next();
game.next();
game.undo();
assertEquals(Board.BLACK, game.board.get(0, 0));
assertEquals(Board.WHITE, game.board.get(1, 1));
assertEquals(Board.NONE, game.board.get(2, 2));
game.undo();
assertEquals(Board.NONE, game.board.get(0, 0));