return backingIterator().previousIndex();
  }

  @Override
  public void set(@ParametricNullness T element) {
    throw new UnsupportedOperationException();
  }

  @Override
  public void add(@ParametricNullness T element) {
    throw new UnsupportedOperationException();
  }

    @Test
    @DisplayName("Remove propagates UnsupportedOperationException")
    void removeException() {
        when(delegate.hasNext()).thenReturn(false);
        doThrow(new UnsupportedOperationException("Not supported")).when(delegate).remove();

        TestIterator iterator = new TestIterator(null);

        UnsupportedOperationException ex = assertThrows(UnsupportedOperationException.class, iterator::remove);

        try {
            result.getRelevantDocIds().add("newDoc");
            fail("DocIds list should be immutable");
        } catch (UnsupportedOperationException e) {
            // Expected
        }
    }

    @Test
    public void test_indexesAreImmutable() {
        List<String> docIds = Arrays.asList("doc1", "doc2");

            char.class,
            double.class,
            float.class,
            int.class,
            long.class,
            short.class,
            void.class);

    assertThrows(UnsupportedOperationException.class, () -> primitives.remove(boolean.class));
  }

  public void testAllWrapperTypes() {
    Set<Class<?>> wrappers = Primitives.allWrapperTypes();
    assertThat(wrappers)
        .containsExactly(

  @Override
  @Test
  public void nodes_checkReturnedSetMutability() {
    assume().that(graphIsMutable()).isTrue();

    Set<Integer> nodes = graph.nodes();
    assertThrows(UnsupportedOperationException.class, () -> nodes.add(N2));
    addNode(N1);
    assertThat(graph.nodes()).containsExactlyElementsIn(nodes);
  }

  @Override
  @Test
  public void adjacentNodes_checkReturnedSetMutability() {

  @Override
  public boolean isEmpty() {
    return asRanges().isEmpty();
  }

  @Override
  public void add(Range<C> range) {
    throw new UnsupportedOperationException();
  }

  @Override
  public void remove(Range<C> range) {
    throw new UnsupportedOperationException();
  }

  @Override
  public void clear() {
    remove(Range.all());
  }

  @Override
  public boolean enclosesAll(RangeSet<C> other) {

  public void testAddAll_unsupportedNothing() {
    try {
      assertFalse(
          "addAll(nothing) should return false or throw", collection.addAll(emptyCollection()));
    } catch (UnsupportedOperationException tolerated) {
    }
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_supportedNonePresent() {
    assertTrue(

    super(true, true, false, false, false);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    throw new UnsupportedOperationException();
  }

  @Override
  protected Map<String, Integer> makeEmptyMap() {
    throw new UnsupportedOperationException();
  }

  @Override
  Table<String, Character, Integer> makeTable() {

    }

    @Override
    public K getKey() {
      throw new UnsupportedOperationException();
    }

    @Override
    public long getAccessTime() {
      throw new UnsupportedOperationException();
    }

    @Override
    public void setAccessTime(long time) {
      throw new UnsupportedOperationException();
    }

    @Override

   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final @Nullable V forcePut(K key, V value) {
    throw new UnsupportedOperationException();
  }

  /**