@Test
public void
acceptance_test() {

    List<Position> board = Arrays.asList(pos(0, 3),pos(1, 5), pos(2, 7), pos(3, 1),
            pos(4, 6), pos(5, 0), pos(6, 2), pos(7, 4));
    assertTrue(EightQueens.isSolution(board));
}