// Make sure computeNext() doesn't get invoked again
    assertFalse(iter.hasNext());

    assertThrows(NoSuchElementException.class, iter::next);
  }

  public void testSneakyThrow() throws Exception {
    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          boolean haveBeenCalled;

          @Override
          public Integer computeNext() {
            if (haveBeenCalled) {

    // second, then signals that it's reached the end of the data
    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          private int rep;

          @Override
          public @Nullable Integer computeNext() {
            switch (rep++) {
              case 0:
                return 0;
              case 1:
                return 1;
              case 2:
                return endOfData();
              default:

    // second, then signals that it's reached the end of the data
    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          private int rep;

          @Override
          public @Nullable Integer computeNext() {
            switch (rep++) {
              case 0:
                return 0;
              case 1:
                return 1;
              case 2:
                return endOfData();
              default:

        // TODO(lowasser): consider making the entries live views
        return new AbstractIterator<Entry<E>>() {
          @Override
          @CheckForNull
          protected Entry<E> computeNext() {
            if (iterator1.hasNext()) {
              Entry<? extends E> entry1 = iterator1.next();
              E element = entry1.getElement();

        // TODO(lowasser): consider making the entries live views
        return new AbstractIterator<Entry<E>>() {
          @Override
          @CheckForNull
          protected Entry<E> computeNext() {
            if (iterator1.hasNext()) {
              Entry<? extends E> entry1 = iterator1.next();
              E element = entry1.getElement();

                  .values()
                  .iterator();
          return new AbstractIterator<Entry<Range<K>, V>>() {

            @Override
            @CheckForNull
            protected Entry<Range<K>, V> computeNext() {
              if (backingItr.hasNext()) {
                RangeMapEntry<K, V> entry = backingItr.next();
                if (entry.getUpperBound().compareTo(subRange.lowerBound) <= 0) {

      return new AbstractIterator<Entry<K, V>>() {
        private int index = -1;
        private final int maxIndex = keyToIndex().size();

        @Override
        @CheckForNull
        protected Entry<K, V> computeNext() {
          for (index++; index < maxIndex; index++) {
            V value = getValue(index);
            if (value != null) {
              return immutableEntry(getKey(index), value);
            }
          }

      return new AbstractIterator<C>() {
        final Iterator<Range<C>> rangeItr = ranges.iterator();
        Iterator<C> elemItr = emptyIterator();

        @Override
        @CheckForNull
        protected C computeNext() {
          while (!elemItr.hasNext()) {
            if (rangeItr.hasNext()) {
              elemItr = ContiguousSet.create(rangeItr.next(), domain).iterator();
            } else {
              return endOfData();

      this.nextPermutation = Lists.newArrayList(list);
      this.comparator = comparator;
    }

    @Override
    @CheckForNull
    protected List<E> computeNext() {
      if (nextPermutation == null) {
        return endOfData();
      }
      ImmutableList<E> next = ImmutableList.copyOf(nextPermutation);
      calculateNextPermutation();
      return next;
    }

    PostOrderIterator(T root) {
      this.stack = new ArrayDeque<>();
      stack.addLast(expand(root));
    }

    @Override
    @CheckForNull
    protected T computeNext() {
      while (!stack.isEmpty()) {
        PostOrderNode<T> top = stack.getLast();
        if (top.childIterator.hasNext()) {
          T child = top.childIterator.next();
          stack.addLast(expand(child));