expectReturnsFalse(containsDuplicates);
    expectContents(e0());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testRetainAll_containsDuplicatesSizeSeveral() {
    expectReturnsTrue(containsDuplicates);
    expectContents(e0());
  }

  // retainAll(nullSingleton)

  protected C resetContainer(C newValue) {
    container = newValue;
    return container;
  }

  /**
   * @see #expectContents(java.util.Collection)
   * @param elements expected contents of {@link #container}
   */
  protected final void expectContents(E... elements) {
    expectContents(Arrays.asList(elements));
  }

  /**
   * Asserts that the collection under test contains exactly the given elements, respecting

  public void testPutPresentKeyDifferentValue() {
    getMap().put(k0(), v0());
    getMap().put(k0(), v1());
    // verify that the bimap is changed, and that the old inverse mapping
    // from v1 -> v0 is deleted
    expectContents(Helpers.mapEntry(k0(), v1()));
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(ZERO)
  public void putDistinctKeysDistinctValues() {
    getMap().put(k0(), v0());
    getMap().put(k1(), v1());

    expectReturnsFalse(containsDuplicates);
    expectContents(e0());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testRetainAll_containsDuplicatesSizeSeveral() {
    expectReturnsTrue(containsDuplicates);
    expectContents(e0());
  }

  // retainAll(nullSingleton)

  public void testPutPresentKeyDifferentValue() {
    getMap().put(k0(), v0());
    getMap().put(k0(), v1());
    // verify that the bimap is changed, and that the old inverse mapping
    // from v1 -> v0 is deleted
    expectContents(Helpers.mapEntry(k0(), v1()));
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(ZERO)
  public void putDistinctKeysDistinctValues() {
    getMap().put(k0(), v0());
    getMap().put(k1(), v1());

  protected C resetContainer(C newValue) {
    container = newValue;
    return container;
  }

  /**
   * @see #expectContents(java.util.Collection)
   * @param elements expected contents of {@link #container}
   */
  protected final void expectContents(E... elements) {
    expectContents(Arrays.asList(elements));
  }

  /**
   * Asserts that the collection under test contains exactly the given elements, respecting

  /**
   * {@inheritDoc}
   *
   * <p>The {@code AbstractListTester} implementation overrides {@link
   * AbstractCollectionTester#expectContents(Collection)} to verify that the order of the elements
   * in the list under test matches what is expected.
   */
  @Override
  protected void expectContents(Collection<E> expectedCollection) {
    List<E> expectedList = Helpers.copyToList(expectedCollection);

      Entry<K, V> entry) {
    return Helpers.mapEntry(entry.getValue(), entry.getKey());
  }

  @Override
  protected void expectContents(Collection<Entry<K, V>> expected) {
    super.expectContents(expected);
    List<Entry<V, K>> reversedEntries = new ArrayList<>();
    for (Entry<K, V> entry : expected) {
      reversedEntries.add(reverseEntry(entry));
    }

      Entry<K, V> entry) {
    return Helpers.mapEntry(entry.getValue(), entry.getKey());
  }

  @Override
  protected void expectContents(Collection<Entry<K, V>> expected) {
    super.expectContents(expected);
    List<Entry<V, K>> reversedEntries = new ArrayList<>();
    for (Entry<K, V> entry : expected) {
      reversedEntries.add(reverseEntry(entry));
    }

  protected Entry<K, V> entry(K key, V value) {
    return Helpers.mapEntry(key, value);
  }

  @Override
  protected void expectContents(Collection<Entry<K, V>> expected) {
    // TODO: move this to invariant checks once the appropriate hook exists?
    super.expectContents(expected);
    for (Entry<K, V> entry : expected) {
      assertEquals(