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

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

  // retainAll(nullSingleton)

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

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

  // retainAll(nullSingleton)

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeySupported() {
    initMapWithNullKey();
    expectContents(createArrayWithNullKey());
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeyUnsupported() {

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeySupported() {
    initMapWithNullKey();
    expectContents(createArrayWithNullKey());
  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNullKeyUnsupported() {

        getValueForNullKey(),
        put(newEntry));

    Entry<K, V>[] expected = createArrayWithNullKey();
    expected[getNullLocation()] = newEntry;
    expectContents(expected);
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPut_nullKeyUnsupported() {
    assertThrows(NullPointerException.class, () -> put(nullKeyEntry));

        getValueForNullKey(),
        put(newEntry));

    Entry<K, V>[] expected = createArrayWithNullKey();
    expected[getNullLocation()] = newEntry;
    expectContents(expected);
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPut_nullKeyUnsupported() {
    assertThrows(NullPointerException.class, () -> put(nullKeyEntry));

    expectContents(expected);
  }

  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testSubList_subListClearAffectsOriginal() {
    List<E> subList = getList().subList(0, 1);
    subList.clear();
    List<E> expected = asList(createSamplesArray()).subList(1, getNumElements());
    expectContents(expected);
  }

  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNull_supported() {
    E[] array = createArrayWithNullElement();
    collection = getSubjectGenerator().create(array);
    expectContents(array);
  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testCreateWithNull_unsupported() {
    E[] array = createArrayWithNullElement();

    collection = getSubjectGenerator().create(array);
    assertTrue("add(nullPresent) should return true", getList().add(null));

    List<E> expected = copyToList(array);
    expected.add(null);
    expectContents(expected);
  }

  /**
   * Returns the {@link Method} instance for {@link #testAdd_supportedNullPresent()} so that tests
   * can suppress it. See {@link CollectionAddTester#getAddNullSupportedMethod()} for details.

      protected ListIterator<E> newTargetIterator() {
        resetCollection();
        return getList().listIterator();
      }

      @Override
      protected void verify(List<E> elements) {
        expectContents(elements);
      }
    }.test();
  }

  public void testListIterator_tooLow() {
    assertThrows(IndexOutOfBoundsException.class, () -> getList().listIterator(-1));
  }