assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());
    assertEquals("[" + JOINER.join(map.values()) + "]", map.values().toString());

    assertEquals(new HashSet<>(map.entrySet()), map.entrySet());
    assertEquals(new HashSet<>(map.keySet()), map.keySet());
  }

    create().putAll(new HashMap<String, Integer>());
  }

  public void testKeySet() {
    Map<String, Integer> map = create();
    Set<String> keySet = map.keySet();
    assertTrue(keySet instanceof SynchronizedSet);
    assertSame(mutex, ((SynchronizedSet<?>) keySet).mutex);
  }

  public void testValues() {
    Map<String, Integer> map = create();
    Collection<Integer> values = map.values();

    assertThat(multimap.keySet()).containsExactly("foo", "bar", "cow").inOrder();
    assertThat(multimap.removeAll("foo")).containsExactly(6, 7).inOrder();
    assertThat(multimap.keySet()).containsExactly("bar", "cow").inOrder();
    assertTrue(multimap.remove("bar", 4));
    assertThat(multimap.keySet()).containsExactly("bar", "cow").inOrder();
    assertTrue(multimap.remove("bar", 1));

                        ArrayTable.create(rowKeys, columnKeys);
                    populateForRowKeySet(table, elements);
                    return table.column(1).keySet();
                  }
                })
            .named("ArrayTable.column.keySet")
            .withFeatures(
                CollectionSize.ONE,
                CollectionSize.SEVERAL,
                CollectionFeature.KNOWN_ORDER,

      Set<Object> keys = cache.asMap().keySet();
      assertThrows(NullPointerException.class, () -> keys.toArray((Object[]) null));
      checkEmpty(cache);
    }
  }

  public void testKeySet_addNotSupported() {
    for (LoadingCache<Object, Object> cache : caches()) {
      assertThrows(UnsupportedOperationException.class, () -> cache.asMap().keySet().add(1));

      assertThrows(

      return delegate;
    }

    @Override
    public Set<K> keySet() {
      return new ForwardingSet<K>() {
        @Override
        protected Set<K> delegate() {
          return delegate.keySet();
        }

        @Override
        public Iterator<K> iterator() {
          return Iterators.unmodifiableIterator(delegate.keySet().iterator());
        }

        @Override

      Set<Object> keys = cache.asMap().keySet();
      assertThrows(NullPointerException.class, () -> keys.toArray((Object[]) null));
      checkEmpty(cache);
    }
  }

  public void testKeySet_addNotSupported() {
    for (LoadingCache<Object, Object> cache : caches()) {
      assertThrows(UnsupportedOperationException.class, () -> cache.asMap().keySet().add(1));

      assertThrows(

    assertTrue(multimap().containsKey(k0()));
  }

  public void testContainsKeyNo() {
    assertFalse(multimap().containsKey(k3()));
  }

  public void testContainsKeysFromKeySet() {
    for (K k : multimap().keySet()) {
      assertTrue(multimap().containsKey(k));
    }
  }

  public void testContainsKeyAgreesWithGet() {
    for (K k : sampleKeys()) {
      assertEquals(!multimap().get(k).isEmpty(), multimap().containsKey(k));

    EnumBiMap<Currency, Country> bimap = EnumBiMap.create(map);

    Iterator<Currency> iter = bimap.keySet().iterator();
    assertEquals(Currency.DOLLAR, iter.next());
    iter.remove();

    // forward map ordered by currency
    assertThat(bimap.keySet()).containsExactly(Currency.FRANC, Currency.PESO).inOrder();
    // forward map ordered by currency (even for country values)

    KeySet(Map<K, Collection<V>> subMap) {
      super(subMap);
    }

    @Override
    public Iterator<K> iterator() {
      Iterator<Entry<K, Collection<V>>> entryIterator = map().entrySet().iterator();
      return new Iterator<K>() {
        @Nullable Entry<K, Collection<V>> entry;

        @Override
        public boolean hasNext() {
          return entryIterator.hasNext();