/**
   * Indicates that a collection disallows certain elements (other than {@code null}, whose validity
   * as an element is indicated by the presence or absence of {@link #ALLOWS_NULL_VALUES}). From the
   * documentation for {@link Collection}:
   *
   * <blockquote>
   *
   * "Some collection implementations have restrictions on the elements that they may contain. For

   * contains(). Verify that these sets are consistent with the elements of their iterator.
   */
  @CanIgnoreReturnValue
  static <T> Set<T> sanityCheckSet(Set<T> set) {
    assertThat(set).hasSize(Iterators.size(set.iterator()));
    for (Object element : set) {
      assertThat(set).contains(element);
    }
    assertThat(set).doesNotContain(new Object());

    @Override
    public boolean addAll(int index, Collection<? extends V> elements) {
      checkNotNull(elements);
      checkPositionIndex(index, 0);
      throw new IllegalArgumentException("Key does not satisfy predicate: " + key);
    }

    @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types
    @Override
    protected List<V> delegate() {
      return emptyList();
    }

import java.util.Collection;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;
import org.junit.Ignore;

/**
 * Base class for collection testers.
 *
 * @param <E> the element type of the collection to be tested.
 * @author Kevin Bourrillion
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

            }
        }

        /**
         * Gets the element name to use for comparison.
         * Prefers qName (which includes namespace prefix) but falls back to localName if qName is empty.
         * @param localName the local name without namespace prefix
         * @param qName the qualified name with namespace prefix
         * @return the element name to use
         */

      Comparator<? super E> comparator, E... elements) {
    checkNotNull(elements);
    switch (elements.length) {
      case 0:
        return emptySet(comparator);
      default:
        SortedSet<E> delegate = new TreeSet<E>(comparator);
        for (E element : elements) {
          checkNotNull(element);
          delegate.add(element);
        }

   * IllegalArgumentException}.
   */
  @Override
  boolean allowsSelfLoops();

  /** Returns the order of iteration for the elements of {@link #nodes()}. */
  @Override
  ElementOrder<N> nodeOrder();

  /**
   * Returns an {@link ElementOrder} that specifies the order of iteration for the elements of
   * {@link #edges()}, {@link #adjacentNodes(Object)}, {@link #predecessors(Object)}, {@link

  public void testHashCode() {
    int expectedHashCode = 1;
    for (E element : getOrderedElements()) {
      expectedHashCode = 31 * expectedHashCode + ((element == null) ? 0 : element.hashCode());
    }
    assertEquals(
        "A List's hashCode() should be computed from those of its elements.",
        expectedHashCode,
        getList().hashCode());
  }

  /**

   * though we also allow it to "succeed" if neither is permitted.
   */

  private void assertSetCount(E element, int count) {
    setCountCheckReturnValue(element, count);

    assertEquals(
        "multiset.count() should return the value passed to setCount()",
        count,
        getMultiset().count(element));

    int size = 0;
    for (Multiset.Entry<E> entry : getMultiset().entrySet()) {

    @DisplayName("Should handle various element counts")
    @ValueSource(ints = { 1, 2, 5, 10, 20, 50, 100 })
    void testJoinWithVariousElementCounts(int count) {
        CharSequence[] elements = new CharSequence[count];
        for (int i = 0; i < count; i++) {
            elements[i] = String.valueOf(i);
        }
        String result = StringUtil.join(",", elements);

        // Verify result contains all elements