* List<String> actualElements =
 *     Collections.unmodifiableList(
 *         Arrays.asList("a", "b", "c", "d", "e"));
 * IteratorTester<String> iteratorTester =
 *     new IteratorTester<String>(
 *         6,
 *         IteratorFeature.UNMODIFIABLE,
 *         expectedElements,
 *         IteratorTester.KnownOrder.KNOWN_ORDER) {
 *       @Override
 *       protected Iterator<String> newTargetIterator() {

 * List<String> actualElements =
 *     Collections.unmodifiableList(
 *         Arrays.asList("a", "b", "c", "d", "e"));
 * IteratorTester<String> iteratorTester =
 *     new IteratorTester<String>(
 *         6,
 *         IteratorFeature.UNMODIFIABLE,
 *         expectedElements,
 *         IteratorTester.KnownOrder.KNOWN_ORDER) {
 *       @Override
 *       protected Iterator<String> newTargetIterator() {

  @CollectionFeature.Require({SUPPORTS_ITERATOR_REMOVE, KNOWN_ORDER})
  public void testRemovingIteratorKnownOrder() {
    new IteratorTester<E>(
        4,
        MODIFIABLE,
        getSubjectGenerator().order(asList(e0(), e1(), e1(), e2())),
        IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<E> newTargetIterator() {

    new IteratorTester<Integer>(
        3, MODIFIABLE, newArrayList(1, 2), IteratorTester.KnownOrder.UNKNOWN_ORDER) {
      @Override
      protected Iterator<Integer> newTargetIterator() {
        return newArrayList(2, 1).iterator();
      }
    }.test();
  }

  public void testUnknownOrderUnrecognizedElement() {
    IteratorTester<Integer> tester =
        new IteratorTester<Integer>(

  public void testIterator_knownOrderRemoveSupported() {
    runIteratorTest(MODIFIABLE, IteratorTester.KnownOrder.KNOWN_ORDER, getOrderedElements());
  }

  @CollectionFeature.Require(value = KNOWN_ORDER, absent = SUPPORTS_ITERATOR_REMOVE)
  public void testIterator_knownOrderRemoveUnsupported() {
    runIteratorTest(UNMODIFIABLE, IteratorTester.KnownOrder.KNOWN_ORDER, getOrderedElements());
  }

  @CollectionFeature.Require({SUPPORTS_ITERATOR_REMOVE, KNOWN_ORDER})
  public void testRemovingIteratorKnownOrder() {
    new IteratorTester<E>(
        4,
        MODIFIABLE,
        getSubjectGenerator().order(asList(e0(), e1(), e1(), e2())),
        IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<E> newTargetIterator() {

  private abstract static class EmptyIteratorTester extends IteratorTester<Integer> {
    EmptyIteratorTester() {
      super(3, MODIFIABLE, Collections.<Integer>emptySet(), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

  @GwtIncompatible // Only used by @GwtIncompatible code
  private abstract static class SingletonIteratorTester extends IteratorTester<Integer> {
    SingletonIteratorTester() {

  private abstract static class EmptyIteratorTester extends IteratorTester<Integer> {
    EmptyIteratorTester() {
      super(3, MODIFIABLE, Collections.<Integer>emptySet(), IteratorTester.KnownOrder.KNOWN_ORDER);
    }
  }

  @GwtIncompatible // Only used by @GwtIncompatible code
  private abstract static class SingletonIteratorTester extends IteratorTester<Integer> {
    SingletonIteratorTester() {

@GwtCompatible
@NullMarked
public class PeekingIteratorTest extends TestCase {

  /**
   * Version of {@link IteratorTester} that compares an iterator over a given collection of elements
   * (used as the reference iterator) against a {@code PeekingIterator} that *wraps* such an
   * iterator (used as the target iterator).
   *
   * <p>This IteratorTester makes copies of the master so that it can later verify that {@link

        }
      }.test();
    }
  }

  @GwtIncompatible // unreasonably slow
  public void testKeysIteration() {
    new IteratorTester<String>(
        6,
        MODIFIABLE,
        newArrayList("foo", "foo", "bar", "bar", "foo"),
        IteratorTester.KnownOrder.KNOWN_ORDER) {
      private @Nullable Multimap<String, Integer> multimap;

      @Override