assertThrows(NoSuchElementException.class, () -> iterator.previous());
    assertThrows(UnsupportedOperationException.class, () -> iterator.remove());
    assertThrows(UnsupportedOperationException.class, () -> iterator.set("a"));
    assertThrows(UnsupportedOperationException.class, () -> iterator.add("a"));
  }

  public void testEmptyModifiableIterator() {

  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testSetCountConditional_negativeOldCount_addUnsupported() {
    try {
      assertSetCountNegativeOldCount();
    } catch (UnsupportedOperationException tolerated) {
    }
  }

  // Incorrect expected present count.

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testSetCountConditional_oldCountTooLarge() {
    assertFalse(

        if (!iterator.hasNext()) {
          iterator = iterable.iterator();
        }
        return iterator.next();
      }

      @Override
      public void remove() {
        throw new UnsupportedOperationException();
      }
    };
  }

  static <T extends @Nullable Object> T get(Iterator<T> iterator, int position) {
    for (int i = 0; i < position; i++) {
      iterator.next();
    }

              endOfData();
            }
            haveBeenCalled = true;
            return 0;
          }
        };

    assertEquals(0, (int) iter.next());

    assertThrows(UnsupportedOperationException.class, iter::remove);
  }

  public void testReentrantHasNext() {
    Iterator<Integer> iter =
        new AbstractIterator<Integer>() {
          @Override

     *         any.
     */
    public PersistedToolchains read(XmlPullParser parser, boolean strict) throws IOException, XmlPullParserException {
        throw new UnsupportedOperationException("Not yet implemented");
    }

    /**
     * @param reader a reader object.
     * @param strict a strict object.
     * @return PersistedToolchains
     * @throws IOException IOException if any.

            } catch (Exception e) {
                throw new RuntimeException("Unable to create repository", e);
            }
        } else {
            // TODO
            throw new UnsupportedOperationException("Not yet implemented");
        }
    }

   */
  private static class DiesOnIteratorArrayList extends ArrayList<String> {
    /**
     * @throws UnsupportedOperationException all the time
     */
    @Override
    public Iterator<String> iterator() {
      throw new UnsupportedOperationException();
    }
  }

  public void testGetLast_withDefault_not_empty_list() {
    // TODO: verify that this is the best testing strategy.

                throw new IllegalArgumentException();
              }

              @Override
              public Integer next() {
                // Wrong exception type.
                throw new UnsupportedOperationException();
              }

              @Override
              public boolean hasNext() {
                return false;
              }
            };
          }
        };

  }

  /**
   * Specifies whether the graph will allow self-loops (edges that connect a node to itself).
   * Attempting to add a self-loop to a graph that does not allow them will throw an {@link
   * UnsupportedOperationException}.
   *
   * <p>The default value is {@code false}.
   */
  @CanIgnoreReturnValue
  public ValueGraphBuilder<N, V> allowsSelfLoops(boolean allowsSelfLoops) {
    this.allowsSelfLoops = allowsSelfLoops;

    assertEquals(asList(b, c), copyToList(sortedMultiset.entrySet()));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  public void testPollFirstUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> sortedMultiset.pollFirstEntry());
  }

  @CollectionSize.Require(SEVERAL)
  public void testLower() {
    resetWithHole();