assertEquals(HashMultiset.create(asList("a", "b", "a", "c")), multiset);
  }

  public void testBuilderAddAll() {
    List<String> a = asList("a", "b");
    List<String> b = asList("c", "d");
    ImmutableMultiset<String> multiset =
        new ImmutableMultiset.Builder<String>().addAll(a).addAll(b).build();
    assertEquals(HashMultiset.create(asList("a", "b", "c", "d")), multiset);
  }

    FluentIterable<Integer> result =
        FluentIterable.<Integer>from(asList(1, 2, 3)).append(Lists.newArrayList(4, 5, 6));
    assertEquals(asList(1, 2, 3, 4, 5, 6), Lists.newArrayList(result));
    assertEquals("[1, 2, 3, 4, 5, 6]", result.toString());

    result = FluentIterable.<Integer>from(asList(1, 2, 3)).append(4, 5, 6);
    assertEquals(asList(1, 2, 3, 4, 5, 6), Lists.newArrayList(result));

        multimap = LinkedHashMultimap.create();
        multimap.putAll("foo", asList(2, 3));
        multimap.putAll("bar", asList(4, 5));
        multimap.putAll("foo", asList(6));
        multimap.putAll("baz", asList(7, 8));
        multimap.putAll("dog", asList(9));
        multimap.putAll("bar", asList(10, 11));
        multimap.putAll("cat", asList(12, 13, 14));
        return multimap.asMap().entrySet().iterator();
      }

        Sets.newLinkedHashSet(
            asList(
                Maps.immutableEntry("foo", (Collection<Integer>) asList(2, 3, 6)),
                Maps.immutableEntry("bar", (Collection<Integer>) asList(4, 5, 10, 11)),
                Maps.immutableEntry("baz", (Collection<Integer>) asList(7, 8)),
                Maps.immutableEntry("dog", (Collection<Integer>) asList(9)),

    Multiset<String> ms2 = HashMultiset.create(Arrays.asList("a"));
    assertThat(Multisets.difference(ms1, ms2)).containsExactly("a", "b");
  }

  public void testDifferenceWithRemovedElement() {
    Multiset<String> ms1 = HashMultiset.create(Arrays.asList("a", "b", "a"));
    Multiset<String> ms2 = HashMultiset.create(Arrays.asList("b"));

    assertEquals(HashMultiset.create(asList("a", "b", "a", "c")), multiset);
  }

  public void testBuilderAddAll() {
    List<String> a = asList("a", "b");
    List<String> b = asList("c", "d");
    ImmutableMultiset<String> multiset =
        new ImmutableMultiset.Builder<String>().addAll(a).addAll(b).build();
    assertEquals(HashMultiset.create(asList("a", "b", "c", "d")), multiset);
  }

    Multiset<String> ms2 = HashMultiset.create(Arrays.asList("a"));
    assertThat(Multisets.difference(ms1, ms2)).containsExactly("a", "b");
  }

  public void testDifferenceWithRemovedElement() {
    Multiset<String> ms1 = HashMultiset.create(Arrays.asList("a", "b", "a"));
    Multiset<String> ms2 = HashMultiset.create(Arrays.asList("b"));

    fromList.set(0, 5);
    assertEquals(asList(4, 3, 2, 5), toList);
    fromList.add(6);
    assertEquals(asList(6, 4, 3, 2, 5), toList);
    fromList.add(2, 9);
    assertEquals(asList(6, 4, 3, 9, 2, 5), toList);
    fromList.remove(Integer.valueOf(2));
    assertEquals(asList(6, 4, 3, 9, 5), toList);
    fromList.remove(3);
    assertEquals(asList(6, 3, 9, 5), toList);

    // A few elements.
    a = asList(4, 8, 15, 16, 23, 42);
    b = asList(4, 8, 15, 16, 23, 42);
    assertTrue(Iterables.elementsEqual(a, b));

    // An element differs.
    a = asList(4, 8, 15, 12, 23, 42);
    b = asList(4, 8, 15, 16, 23, 42);
    assertFalse(Iterables.elementsEqual(a, b));

    // null versus non-null.
    a = Arrays.<@Nullable Integer>asList(4, 8, 15, null, 23, 42);

    fromList.set(0, 5);
    assertEquals(asList(4, 3, 2, 5), toList);
    fromList.add(6);
    assertEquals(asList(6, 4, 3, 2, 5), toList);
    fromList.add(2, 9);
    assertEquals(asList(6, 4, 3, 9, 2, 5), toList);
    fromList.remove(Integer.valueOf(2));
    assertEquals(asList(6, 4, 3, 9, 5), toList);
    fromList.remove(3);
    assertEquals(asList(6, 3, 9, 5), toList);