public void testContainsAll() {
    ImmutableSortedSet<Integer> set = ContiguousSet.create(Range.closed(1, 3), integers());
    for (Set<Integer> subset : Sets.powerSet(ImmutableSet.of(1, 2, 3))) {
      assertTrue(set.containsAll(subset));
    }
    for (Set<Integer> subset : Sets.powerSet(ImmutableSet.of(1, 2, 3))) {
      assertFalse(set.containsAll(Sets.union(subset, ImmutableSet.of(9))));
    }
  }

  public void testContainsAll() {
    ImmutableSortedSet<Integer> set = ContiguousSet.create(Range.closed(1, 3), integers());
    for (Set<Integer> subset : Sets.powerSet(ImmutableSet.of(1, 2, 3))) {
      assertTrue(set.containsAll(subset));
    }
    for (Set<Integer> subset : Sets.powerSet(ImmutableSet.of(1, 2, 3))) {
      assertFalse(set.containsAll(Sets.union(subset, ImmutableSet.of(9))));
    }
  }

            Range.closed(4, 6),
            Range.closedOpen(1, 3),
            Range.openClosed(5, 7),
            Range.open(3, 4));
    subsets:
    for (Set<Range<Integer>> subset : Sets.powerSet(ranges)) {
      assertEquals(TreeRangeSet.create(subset), ImmutableRangeSet.unionOf(subset));

      RangeSet<Integer> mutable = TreeRangeSet.create();