@Test 
    public void deFlagStartNotInBoard(){
        Board board = new Board(3);
        board.setCellState(1, 1, "dug");
        board.setCellState(0, 0, "flagged");
        String output = board.deFlag(-1, 0);
        String expected = "F - -" + "/n" +
                          "-   -" + "/n" +
                          "- - -" + "/n";
        assertEquals(expected, output);
    }