@Test
    public void flagStartNotInBoard(){
        Board board = new Board(3);
        board.setCellState(1, 1, "dug");
        board.setCellBomb(0, 0, true);
        String output = board.flag(-1, 1);
        String expected = "- - -" + "/n" +
                          "- 1 -" + "/n" +
                          "- - -" + "/n";
        assertEquals(expected, output);
    }