def test_board_is_full_when_all_spaces_are_occupied():
    board = Board(['x', 'x', 'x', 'x', 'x', 'x', 'x', 'x', 'x'])

    assert board.is_full() is True
def test_board_is_not_full_when_only_some_spaces_are_occupied():
    board = Board(['x', 'x', 'x', 'x', 'x', 'x', 'x', 'x', '9'])

    assert board.is_full() is False