Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }

    Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }

    Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }

    return Multisets.immutableEntry(element, count);
  }

  private static <E extends @Nullable Object> Entry<E> control(E element, int count) {
    return HashMultiset.create(nCopies(count, element)).entrySet().iterator().next();
  }

  public void testToString() {
    assertEquals("foo", entry("foo", 1).toString());
    assertEquals("bar x 2", entry("bar", 2).toString());
  }

    SerializableTester.reserializeAndAssert(multimap.asMap());
    Collection<Integer> valuesCopy = SerializableTester.reserialize(multimap.values());
    assertEquals(HashMultiset.create(multimap.values()), HashMultiset.create(valuesCopy));
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testEmptySerialization() {

    SerializableTester.reserializeAndAssert(multimap.asMap());
    Collection<Integer> valuesCopy = SerializableTester.reserialize(multimap.values());
    assertEquals(HashMultiset.create(multimap.values()), HashMultiset.create(valuesCopy));
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testEmptySerialization() {

    return Multisets.immutableEntry(element, count);
  }

  private static <E extends @Nullable Object> Entry<E> control(E element, int count) {
    return HashMultiset.create(nCopies(count, element)).entrySet().iterator().next();
  }

  public void testToString() {
    assertEquals("foo", entry("foo", 1).toString());
    assertEquals("bar x 2", entry("bar", 2).toString());
  }

    SerializableTester.reserializeAndAssert(multimap.asMap());
    Collection<Integer> valuesCopy = SerializableTester.reserialize(multimap.values());
    assertEquals(HashMultiset.create(multimap.values()), HashMultiset.create(valuesCopy));
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester
  public void testEmptySerialization() {

  }

  enum MultisetImpl implements CollectionsImplEnum {
    HashMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {
        return HashMultiset.create(contents);
      }
    },
    LinkedHashMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {

      }
      assertThat(queue).isEmpty();
    }
  }

  public void testRandomAddsAndRemoves() {
    Random random = new Random(0);
    Multiset<Integer> elements = HashMultiset.create();
    MinMaxPriorityQueue<Integer> queue = MinMaxPriorityQueue.create();
    int range = 10_000; // range should be small enough that equal elements occur semi-frequently