import java.util.Collections;
import java.util.Iterator;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A utility for testing an Iterator implementation by comparing its behavior to that of a "known
 * good" reference implementation. In order to accomplish this, it's important to test a great
 * variety of sequences of the {@link Iterator#next}, {@link Iterator#hasNext} and {@link

  }

  public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) {
    Iterator<E> iterator = elements.iterator();
    checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable");
    EnumMap<E, Count> map = new EnumMap<>(getDeclaringClassOrObjectForJ2cl(iterator.next()));
    EnumMultiset<E> multiset = new EnumMultiset<>(map);
    Iterables.addAll(multiset, elements);

      TestSubjectGenerator<? extends Iterable<E>> collectionGenerator) {
    this.collectionGenerator = collectionGenerator;
  }

  @Override
  public TestSubjectGenerator<? extends Iterable<E>> getInnerGenerator() {
    return collectionGenerator;
  }

  @Override
  public Iterator<E> get() {
    return collectionGenerator.createTestSubject().iterator();
  }

   * always true when the iterable has fewer than two elements.
   */
  public static <T extends @Nullable Object> boolean isInOrder(
      Iterable<? extends T> iterable, Comparator<T> comparator) {
    checkNotNull(comparator);
    Iterator<? extends T> it = iterable.iterator();
    if (it.hasNext()) {
      T prev = it.next();
      while (it.hasNext()) {
        T next = it.next();
        if (comparator.compare(prev, next) > 0) {

    expectUnchanged();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutAllOnlyCallsIteratorOnce() {
    Iterable<V> iterable =
        new Iterable<V>() {
          private boolean calledIteratorAlready = false;

          @Override
          public Iterator<V> iterator() {
            checkState(!calledIteratorAlready);
            calledIteratorAlready = true;
            return Iterators.forArray(v3());

   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(Collection<T> collection) {
    // return collection::iterator;
    return new Iterable<T>() {
      @Override
      public Iterator<T> iterator() {
        return collection.iterator();
      }
    };
  }

  public void testEquals() {
    new EqualsTester()

   */
  public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) {
    Iterator<E> iterator = elements.iterator();
    checkArgument(iterator.hasNext(), "EnumMultiset constructor passed empty Iterable");
    EnumMultiset<E> multiset = new EnumMultiset<>(iterator.next().getDeclaringClass());
    Iterables.addAll(multiset, elements);
    return multiset;
  }

  /**

    return new ArrayDeque<>();
  }

  /**
   * Creates an {@code ArrayDeque} containing the elements of the specified iterable, in the order
   * they are returned by the iterable's iterator.
   *
   * @since 12.0
   */
  public static <E> ArrayDeque<E> newArrayDeque(Iterable<? extends E> elements) {
    if (elements instanceof Collection) {
      return new ArrayDeque<>((Collection<? extends E>) elements);
    }

    Iterator<String> iterator = asList("a", "b", "a").iterator();
    List<String> list = ImmutableList.copyOf(iterator);
    assertEquals(asList("a", "b", "a"), list);
  }

  public void testCopyOf_iteratorContainingNull() {
    Iterator<@Nullable String> iterator =
        Arrays.<@Nullable String>asList("a", null, "b").iterator();
    assertThrows(

    return new Iterable<String>() {
      @Override
      public Iterator<String> iterator() {
        return splittingIterator(sequence);
      }

      @Override
      public String toString() {
        return Joiner.on(", ")
            .appendTo(new StringBuilder().append('['), this)
            .append(']')
            .toString();
      }
    };
  }