@Test
public void orderTest() {

    Partition p = new Partition(new int[][]{{1, 3}, {0, 2}});
    p.order();
    SortedSet<Integer> cell0 = p.getCell(0);
    SortedSet<Integer> cell1 = p.getCell(1);
    Assert.assertTrue(cell0.first() < cell1.first());
    Assert.assertTrue(cell0.last() < cell1.last());
}