/** Returns an unmodifiable view of {@code iterable}. */
  public static <T extends @Nullable Object> Iterable<T> unmodifiableIterable(
      Iterable<? extends T> iterable) {
    checkNotNull(iterable);
    if (iterable instanceof UnmodifiableIterable || iterable instanceof ImmutableCollection) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
      Iterable<T> result = (Iterable<T>) iterable;

    }

    /**
     * Creates an {@link IteratorEnumeration}.
     *
     * @param iterable the iterable object (must not be {@literal null})
     */
    public IteratorEnumeration(final Iterable<T> iterable) {
        assertArgumentNotNull("iterable", iterable);
        this.iterator = iterable.iterator();
    }

    @Override
    public boolean hasMoreElements() {
        return iterator.hasNext();

   * already a {@code FluentIterable}.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Collection#stream} if {@code iterable} is a {@link
   * Collection}; {@link Streams#stream(Iterable)} otherwise.
   */
  public static <E extends @Nullable Object> FluentIterable<E> from(Iterable<E> iterable) {
    return (iterable instanceof FluentIterable)
        ? (FluentIterable<E>) iterable

    /**
     * Returns an {@link Iterable} that wraps an {@link IndexedIterator} for use in a for-each statement.
     *
     * @param <T> the element type
     * @param iterable the iterable (must not be {@literal null})
     * @return an {@link Iterable} wrapping an {@link IndexedIterator}
     */
    public static <T> Iterable<Indexed<T>> indexed(final Iterable<T> iterable) {
        assertArgumentNotNull("iterable", iterable);

    }

    @Override
    public Iterable<? extends Character> successors(Character node) {
      requestedNodes.add(node);
      return delegate.successors(node);
    }
  }

  private static <N> SuccessorsFunction<N> fixedSuccessors(Iterable<N> successors) {
    return new SuccessorsFunction<N>() {
      @Override
      public Iterable<N> successors(N n) {
        return successors;
      }

@NullUnmarked
public final class IterablesFilterArrayListTest
    extends AbstractFilteredIterableTest<Iterable<Integer>> {
  @Override
  Iterable<Integer> createUnfiltered(Iterable<Integer> contents) {
    return Lists.newArrayList(contents);
  }

  @Override
  Iterable<Integer> filter(Iterable<Integer> elements, Predicate<? super Integer> predicate) {
    return Iterables.filter(elements, predicate);
  }

  public void testOf_empty() {
    Iterable<String> iterable = MinimalIterable.<String>of();
    Iterator<String> iterator = iterable.iterator();
    assertFalse(iterator.hasNext());
    assertThrows(NoSuchElementException.class, () -> iterator.next());
    assertThrows(IllegalStateException.class, () -> iterable.iterator());
  }

  public void testOf_one() {
    Iterable<String> iterable = MinimalIterable.of("a");

    @SuppressWarnings("rawtypes") // the purpose is to test raw type
    Invokable<?, Iterable> delegate =
        Prepender.method("prepend", String.class, Iterable.class).returning(Iterable.class);
    assertEquals(new TypeToken<Iterable<String>>() {}, delegate.getReturnType());
    @SuppressWarnings("unchecked") // prepend() returns Iterable<String>
    Iterable<String> result = delegate.invoke(null, "a", ImmutableList.of("b", "c"));

      return generator.create(elements);
    }

    @Override
    public Entry<K, V>[] createArray(int length) {
      return generator.createArray(length);
    }

    @Override
    public Iterable<Entry<K, V>> order(List<Entry<K, V>> insertionOrder) {
      return generator.order(insertionOrder);
    }

    @SuppressWarnings("unchecked")
    @Override
    public K[] createKeyArray(int length) {

    Iterable<String> set = newHashSet("a", "b");
    assertFalse(FluentIterable.from(set).contains("c"));
  }

  public void testContains_nonNullIterableYes() {
    Iterable<String> set = iterable("a", null, "b");
    assertTrue(FluentIterable.from(set).contains("b"));
  }

  public void testContains_nonNullIterableNo() {
    Iterable<String> iterable = iterable("a", "b");
    assertFalse(FluentIterable.from(iterable).contains("c"));