Iterable<Character> result = Traverser.forGraph(graph).breadthFirst(charactersOf("ab"));

    assertEqualCharNodes(Iterables.limit(result, 2), "ab");
    assertThat(graph.requestedNodes).containsExactly('a', 'a', 'b', 'b');

    // Iterate again to see if calculation is done again
    assertEqualCharNodes(Iterables.limit(result, 2), "ab");
    assertThat(graph.requestedNodes).containsExactly('a', 'a', 'a', 'b', 'b', 'b');
  }

    Iterable<Character> result = Traverser.forGraph(graph).breadthFirst(charactersOf("ab"));

    assertEqualCharNodes(Iterables.limit(result, 2), "ab");
    assertThat(graph.requestedNodes).containsExactly('a', 'a', 'b', 'b');

    // Iterate again to see if calculation is done again
    assertEqualCharNodes(Iterables.limit(result, 2), "ab");
    assertThat(graph.requestedNodes).containsExactly('a', 'a', 'a', 'b', 'b', 'b');
  }

   */
  protected IteratorTester(
      int steps,
      Iterable<? extends IteratorFeature> features,
      Iterable<E> expectedElements,
      KnownOrder knownOrder) {
    super(steps, Collections.<E>singleton(null), features, expectedElements, knownOrder, 0);
  }

  @Override
  protected final Iterable<Stimulus<E, Iterator<E>>> getStimulusValues() {
    return iteratorStimuli();
  }

    implements Serializable {
  final Equivalence<E> elementEquivalence;

  PairwiseEquivalence(Equivalence<E> elementEquivalence) {
    this.elementEquivalence = Preconditions.checkNotNull(elementEquivalence);
  }

  @Override
  protected boolean doEquivalent(Iterable<T> iterableA, Iterable<T> iterableB) {
    Iterator<T> iteratorA = iterableA.iterator();

      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) {

  // <Integer> needed to prevent warning :(
  private static final Iterable<Integer> ITERABLE_ = Arrays.<Integer>asList();
  private static final Iterable<Integer> ITERABLE_1 = Arrays.asList(1);
  private static final Iterable<Integer> ITERABLE_12 = Arrays.asList(1, 2);
  private static final Iterable<Integer> ITERABLE_123 = Arrays.asList(1, 2, 3);
  private static final Iterable<@Nullable Integer> ITERABLE_NULL = Arrays.asList((Integer) null);

     * @return {@link ClassLoaderIterator}をラップした{@link Iterable}
     */
    public static Iterable<ClassLoader> iterable(final ClassLoader classLoader) {
        return () -> new ClassLoaderIterator(classLoader);
    }

    /**
     * インスタンスを構築します。
     *
     * @param classLoader
     *            クラスローダ。{@literal null}であってはいけません
     */
    public ClassLoaderIterator(final ClassLoader classLoader) {

    POST_ORDER {
      @Override
      <T> Iterable<T> view(T root, TreeTraverser<T> viewer) {
        return viewer.postOrderTraversal(root);
      }
    },
    BREADTH_FIRST {
      @Override
      <T> Iterable<T> view(T root, TreeTraverser<T> viewer) {
        return viewer.breadthFirstTraversal(root);
      }
    };

    abstract <T> Iterable<T> view(T root, TreeTraverser<T> viewer);
  }

    Iterable<Double> iterable = iterable(Collections.<Double>emptySet());
    assertThat(ImmutableDoubleArray.copyOf(iterable)).isSameInstanceAs(ImmutableDoubleArray.of());
  }

  public void testCopyOf_iterable_notCollection_nonempty() {
    List<Double> list = Arrays.asList(0.0, 1.0, 3.0);
    ImmutableDoubleArray iia = ImmutableDoubleArray.copyOf(iterable(list));
    list.set(2, 2.0);

     *
     * @param <E>
     *            要素の型
     * @param iterables
     *            {@link Iterable}の並び。{@literal null}であってはいけません
     * @return {@link MultiIterator}をラップした{@link Iterable}
     */
    public static <E> Iterable<E> iterable(final Iterable<E>... iterables) {
        assertArgumentNotNull("iterables", iterables);

        @SuppressWarnings("unchecked")