SortedSet<Integer> unexpected = Sets.newTreeSet(Ordering.natural());
    unexpected.addAll(asList(1, 2, 3));
    assertFalse(set.containsAll(unexpected));
  }

  public void testContainsAll_differentComparator() {
    Comparator<Comparable<?>> comparator = Collections.reverseOrder();
    SortedSet<String> set =
        new ImmutableSortedSet.Builder<String>(comparator).add("a", "b", "f").build();