for (E e : collection) {
      checkValid(e);
    }
    return delegate.addAll(collection);
  }

  @Override
  public @Nullable E ceiling(E e) {
    return delegate.ceiling(checkValid(e));
  }

  @Override
  public void clear() {
    delegate.clear();
  }

  @Override
  public Comparator<? super E> comparator() {

  @CheckForNull
  public E floor(E element) {
    int index = headIndex(element, true) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  @CheckForNull
  public E ceiling(E element) {
    int index = tailIndex(element, true);
    return (index == size()) ? null : elements.get(index);
  }

  @Override
  @CheckForNull
  public E higher(E element) {

    for (int i = 1; i < n; i++) {
      top.offer(0);
    }
    assertThat(top.topK()).containsExactlyElementsIn(Collections.nCopies(k, 0));
    assertThat(compareCalls[0]).isAtMost(10L * n * IntMath.log2(k, RoundingMode.CEILING));
  }

  public void testExceedMaxIteration() {
    /*
     * Bug #5692 occurred when TopKSelector called Arrays.sort incorrectly.
     */
    TopKSelector<Integer> top = TopKSelector.least(7);

          return Double.MAX_VALUE * sign(x);
        case FLOOR:
          return (roundArbitrarily == Double.POSITIVE_INFINITY)
              ? Double.MAX_VALUE
              : Double.NEGATIVE_INFINITY;
        case CEILING:
          return (roundArbitrarily == Double.POSITIVE_INFINITY)
              ? Double.POSITIVE_INFINITY
              : -Double.MAX_VALUE;
        case UP:
          return roundArbitrarily;
        case UNNECESSARY:

        "next() should still return first element after peeking", "A", peekingIterator.next());

    assertEquals("Should be able to peek() at middle element", "B", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() middle element multiple times", "B", peekingIterator.peek());
    assertEquals(
        "next() should still return middle element after peeking", "B", peekingIterator.next());

    for (int i = 1; i < n; i++) {
      top.offer(0);
    }
    assertThat(top.topK()).containsExactlyElementsIn(Collections.nCopies(k, 0));
    assertThat(compareCalls[0]).isAtMost(10L * n * IntMath.log2(k, RoundingMode.CEILING));
  }

  public void testExceedMaxIteration() {
    /*
     * Bug #5692 occurred when TopKSelector called Arrays.sort incorrectly.
     */
    TopKSelector<Integer> top = TopKSelector.least(7);

        "next() should still return first element after peeking", "A", peekingIterator.next());

    assertEquals("Should be able to peek() at middle element", "B", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() middle element multiple times", "B", peekingIterator.peek());
    assertEquals(
        "next() should still return middle element after peeking", "B", peekingIterator.next());

    for (E e : collection) {
      checkValid(e);
    }
    return delegate.addAll(collection);
  }

  @Override
  public @Nullable E ceiling(E e) {
    return delegate.ceiling(checkValid(e));
  }

  @Override
  public void clear() {
    delegate.clear();
  }

  @Override
  public Comparator<? super E> comparator() {

  // Load factor and capacity for "inner" (i.e. per node/edge element) hash sets or maps
  static final float INNER_LOAD_FACTOR = 1.0f;
  static final int INNER_CAPACITY = 2; // ceiling(EXPECTED_DEGREE / INNER_LOAD_FACTOR)

  // Error messages
  static final String NODE_NOT_IN_GRAPH = "Node %s is not an element of this graph.";
  static final String EDGE_NOT_IN_GRAPH = "Edge %s is not an element of this graph.";