@Test
public void testDescendingKeySetOrder() {

    IncrementalSortMap<Integer, String> map = map5();
    Set s = map.descendingKeySet();
    Iterator i = s.iterator();
    Integer last = (Integer) i.next();
    assertEquals(last, five);
    int count = 1;
    while (i.hasNext()) {
        Integer k = (Integer) i.next();
        assertTrue(last.compareTo(k) > 0);
        last = k;
        ++count;
    }
    assertEquals(5, count);
}