NullPointerException.class, () -> multimap().putAll(k3(), Lists.newArrayList(v3(), null)));

    Collection<V> values = multimap().get(k3());
    if (values.size() == 0) {
      expectUnchanged();
      // Be extra thorough in case internal state was corrupted by the expected null.
      assertEquals(Lists.newArrayList(), Lists.newArrayList(values));
      assertEquals(size, multimap().size());
    } else {

    IteratorTester<Integer> tester =
        new IteratorTester<Integer>(
            4, MODIFIABLE, newArrayList(1, 2, 3), IteratorTester.KnownOrder.KNOWN_ORDER) {
          @Override
          protected Iterator<Integer> newTargetIterator() {
            return Lists.newArrayList(1, 2, 3, 4).iterator();
          }
        };
    assertFailure(tester);
  }

  public void testCanCatchDifferentContents() {

      List<String> list = Lists.newArrayList(elements);
      list.add("zzz");
      return ImmutableSortedSet.copyOf(list).headSet("zzy");
    }
  }

  public static class ImmutableSortedSetTailsetGenerator extends TestStringSortedSetGenerator {
    @Override
    protected SortedSet<String> create(String[] elements) {
      List<String> list = Lists.newArrayList(elements);
      list.add("\0");

    assertNextPermutation(newArrayList(3, 4, 2, 1), permutations);
    assertNextPermutation(newArrayList(3, 2, 4, 1), permutations);
    assertNextPermutation(newArrayList(3, 2, 1, 4), permutations);

    assertNextPermutation(newArrayList(2, 3, 1, 4), permutations);
    assertNextPermutation(newArrayList(2, 3, 4, 1), permutations);
    assertNextPermutation(newArrayList(2, 4, 3, 1), permutations);

    assertNextPermutation(newArrayList(3, 4, 2, 1), permutations);
    assertNextPermutation(newArrayList(3, 2, 4, 1), permutations);
    assertNextPermutation(newArrayList(3, 2, 1, 4), permutations);

    assertNextPermutation(newArrayList(2, 3, 1, 4), permutations);
    assertNextPermutation(newArrayList(2, 3, 4, 1), permutations);
    assertNextPermutation(newArrayList(2, 4, 3, 1), permutations);

    List<Integer> list3 = newArrayList(3);
    input.add(1, list3);

    assertEquals(asList(1, 2, 3, 4), newArrayList(result));
    assertEquals("[1, 2, 3, 4]", result.toString());
  }

  public void testConcatVarargs() {
    List<Integer> list1 = newArrayList(1);
    List<Integer> list2 = newArrayList(4);
    List<Integer> list3 = newArrayList(7, 8);
    List<Integer> list4 = newArrayList(9);

    input.add(1, list3);

    assertEquals(asList(1, 2, 3, 4), newArrayList(result));
    assertEquals("[1, 2, 3, 4]", result.toString());
  }

  public void testConcatVarargs() {
    List<Integer> list1 = newArrayList(1);
    List<Integer> list2 = newArrayList(4);
    List<Integer> list3 = newArrayList(7, 8);
    List<Integer> list4 = newArrayList(9);
    List<Integer> list5 = newArrayList(10);

  public void testEquals() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k1(), v0()), mapEntry(k0(), v3()));
    Map<K, Collection<V>> expected = Maps.newHashMap();
    expected.put(k0(), Lists.newArrayList(v0(), v3()));
    expected.put(k1(), Lists.newArrayList(v0()));
    new EqualsTester().addEqualityGroup(expected, multimap().asMap()).testEquals();
  }

  @CollectionSize.Require(SEVERAL)
  public void testEntrySetEquals() {

  }

  public void testRemoveAll() {
    List<String> list = newArrayList("a", "b", "c", "d", "e");
    assertTrue(Iterators.removeAll(list.iterator(), newArrayList("b", "d", "f")));
    assertEquals(newArrayList("a", "c", "e"), list);
    assertFalse(Iterators.removeAll(list.iterator(), newArrayList("x", "y", "z")));
    assertEquals(newArrayList("a", "c", "e"), list);
  }

  public void testRemoveIf() {

  }

  public void testRemoveAll() {
    List<String> list = newArrayList("a", "b", "c", "d", "e");
    assertTrue(Iterators.removeAll(list.iterator(), newArrayList("b", "d", "f")));
    assertEquals(newArrayList("a", "c", "e"), list);
    assertFalse(Iterators.removeAll(list.iterator(), newArrayList("x", "y", "z")));
    assertEquals(newArrayList("a", "c", "e"), list);
  }

  public void testRemoveIf() {