var got uint64
			iterator := ipIterator(tt.first, tt.last, tt.offset)

			for {
				ip := iterator()
				if !ip.IsValid() {
					break
				}
				got++
			}
			if got != tt.want {
				t.Errorf("ipIterator() = %d, want %d", got, tt.want)
			}
			// check the iterator is fully stopped
			for i := 0; i < 5; i++ {
				if ip := iterator(); ip.IsValid() {

	default:
		offset = uint64(a.rand.Int63n(int64(rangeSize)))
	}
	iterator := ipIterator(a.offsetAddress, a.lastAddress, offset)
	ip, err := a.allocateFromRange(iterator, svc)
	if err == nil {
		return ip, nil
	}
	// check the lower range
	if a.rangeOffset != 0 {
		offset = uint64(a.rand.Intn(a.rangeOffset))
		iterator = ipIterator(a.firstAddress, a.offsetAddress.Prev(), offset)

        iterator.next()
        iterator.next()

        then:
        iterator.previous() == "fuzz"
        iterator.previous() == "fizz"
        iterator.previous() == "foo"
        !iterator.hasPrevious()

        and:
        iterator.next() == "foo"
        iterator.next() == "fizz"
        iterator.next() == "fuzz"
        !iterator.hasNext()

        and:
        iterator.previous() == "fuzz"

    try {
      iterator.next();
      fail();
    } catch (NoSuchElementException expected) {
    }
    try {
      iterable.iterator();
      fail();
    } catch (IllegalStateException expected) {
    }
  }

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

  public void testSize0() {
    Iterator<String> iterator = Iterators.emptyIterator();
    assertEquals(0, Iterators.size(iterator));
  }

  public void testSize1() {
    Iterator<Integer> iterator = Collections.singleton(0).iterator();
    assertEquals(1, Iterators.size(iterator));
  }

  public void testSize_partiallyConsumed() {
    Iterator<Integer> iterator = asList(1, 2, 3, 4, 5).iterator();
    iterator.next();

   */
  static class IteratorWithSunJavaBug6529795<T> implements Iterator<T> {
    Iterator<T> iterator;
    boolean nextThrewException;

    IteratorWithSunJavaBug6529795(Iterator<T> iterator) {
      this.iterator = iterator;
    }

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

    @Override
    public T next() {
      try {

      UnmodifiableIterator<T> iterator) {
    return checkNotNull(iterator);
  }

  /**
   * Returns the number of elements remaining in {@code iterator}. The iterator will be left
   * exhausted: its {@code hasNext()} method will return {@code false}.
   */
  public static int size(Iterator<?> iterator) {
    long count = 0L;
    while (iterator.hasNext()) {
      iterator.next();
      count++;

      UnmodifiableIterator<T> iterator) {
    return checkNotNull(iterator);
  }

  /**
   * Returns the number of elements remaining in {@code iterator}. The iterator will be left
   * exhausted: its {@code hasNext()} method will return {@code false}.
   */
  public static int size(Iterator<?> iterator) {
    long count = 0L;
    while (iterator.hasNext()) {
      iterator.next();
      count++;

        then:
        iterator.hasNext()
        source.iterator().collect() == iterationOrder("foo", "fooz", "fizz", "fuzz")

        when:
        source.add("buzz")
        iterator = source.iterator()
        next = iterator.next()

        then:
        next == "buzz"

        when:
        iterator.remove()

        then:
        iterator.hasNext()

        assertArgumentNotNull("iterator", iterator);

        return () -> new IndexedIterator<>(iterator);
    }

    /**
     *
     * インスタンスを構築します。
     *
     * @param iterator
     *            イテレータ。{@literal null}であってはいけません
     */
    public IndexedIterator(final Iterator<T> iterator) {
        assertArgumentNotNull("iterator", iterator);