NavigableSet<Integer> filtered = filter(createUnfiltered(contents), EVEN);
        NavigableSet<Integer> unfiltered = createUnfiltered(filtered);

        assertEquals(unfiltered.pollLast(), filtered.pollLast());
        assertEquals(unfiltered, filtered);
      }
    }

    public void testNavigation() {
      for (List<Integer> contents : SAMPLE_INPUTS) {

   */

  public void testFilter() {
    FluentIterable<String> filtered =
        FluentIterable.from(asList("foo", "bar")).filter(equalTo("foo"));

    List<String> expected = singletonList("foo");
    List<String> actual = Lists.newArrayList(filtered);
    assertEquals(expected, actual);
    assertCanIterateAgain(filtered);
    assertEquals("[foo]", filtered.toString());
  }

  private static class TypeA {}

    Iterator<String> filtered = filter(unfiltered, equalTo("foo"));
    List<String> expected = singletonList("foo");
    List<String> actual = Lists.newArrayList(filtered);
    assertEquals(expected, actual);
  }

  public void testFilterNoMatch() {
    Iterator<String> unfiltered = Lists.newArrayList("foo", "bar").iterator();
    Iterator<String> filtered = filter(unfiltered, Predicates.alwaysFalse());

    Iterator<String> filtered = filter(unfiltered, equalTo("foo"));
    List<String> expected = singletonList("foo");
    List<String> actual = Lists.newArrayList(filtered);
    assertEquals(expected, actual);
  }

  public void testFilterNoMatch() {
    Iterator<String> unfiltered = Lists.newArrayList("foo", "bar").iterator();
    Iterator<String> filtered = filter(unfiltered, Predicates.alwaysFalse());

      SortedSet<E> set = delegate.create(allEntries.toArray());

      return createSubSet(set, firstExclusive, lastExclusive);
    }

    /** Calls the smallest subSet overload that filters out the extreme values. */
    SortedSet<E> createSubSet(SortedSet<E> set, E firstExclusive, E lastExclusive) {
      if (from == Bound.NO_BOUND && to == Bound.EXCLUSIVE) {
        return set.headSet(lastExclusive);

                unfiltered.add("zzz");
                unfiltered.add("abc");
                return Sets.filter(
                    Sets.filter(unfiltered, Collections2Test.LENGTH_1),
                    Collections2Test.NOT_YYY_ZZZ);
              }
            })
        .named("Sets.filter, filtered input")
        .withFeatures(
            CollectionFeature.SUPPORTS_ADD,
            CollectionFeature.SUPPORTS_REMOVE,

        @SuppressWarnings("unchecked")
        Entry<String, Integer> entry = (Entry<String, Integer>) o;
        multimap.put(entry.getKey(), entry.getValue());
      }
      return filter(multimap);
    }

    abstract ListMultimap<String, Integer> filter(ListMultimap<String, Integer> multimap);

    @Override
    public Collection<Integer> createCollection(Iterable<? extends Integer> values) {
      return Lists.newArrayList(values);

        @SuppressWarnings("unchecked")
        Entry<String, Integer> entry = (Entry<String, Integer>) o;
        multimap.put(entry.getKey(), entry.getValue());
      }
      return filter(multimap);
    }

    abstract ListMultimap<String, Integer> filter(ListMultimap<String, Integer> multimap);

    @Override
    public Collection<Integer> createCollection(Iterable<? extends Integer> values) {
      return Lists.newArrayList(values);

    Multimap<String, Integer> keyFiltered = filterKeys(unfiltered, KEY_PREDICATE);
    Multimap<String, Integer> filtered = filterValues(keyFiltered, VALUE_PREDICATE);
    assertEquals(1, filtered.size());
    assertTrue(filtered.containsEntry("foo", 1));
    assertTrue(filtered.keySet().retainAll(asList("cat", "dog")));
    assertEquals(0, filtered.size());
  }

  // TODO(jlevy): Many more tests needed.

                SortedMultiset<E> multiset =
                    (SortedMultiset<E>) delegate.create(allEntries.toArray());

                // call the smallest subMap overload that filters out the extreme
                // values
                if (from == Bound.INCLUSIVE) {
                  multiset = multiset.tailMultiset(firstInclusive, BoundType.CLOSED);