@GwtCompatible
@NullMarked
public class AbstractSequentialIteratorTest extends TestCase {
  @GwtIncompatible // Too slow
  public void testDoublerExhaustive() {
    new IteratorTester<Integer>(
        3, UNMODIFIABLE, ImmutableList.of(1, 2), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<Integer> newTargetIterator() {
        return newDoubler(1, 2);
      }
    }.test();
  }

import java.util.ListIterator;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A utility similar to {@link IteratorTester} for testing a {@link ListIterator} against a known
 * good reference implementation. As with {@code IteratorTester}, a concrete subclass must provide
 * target iterators on demand. It also requires three additional constructor parameters: {@code

    checkFooBarBazList(list);
    SerializableTester.reserializeAndAssert(list);
    assertTrue(list instanceof RandomAccess);

    new IteratorTester<String>(
        5, UNMODIFIABLE, asList("foo", "bar", "baz"), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<String> newTargetIterator() {
        return Lists.asList("foo", new String[] {"bar", "baz"}).iterator();
      }

  // mode.
  static int listListIteratorTesterNumIterations() {
    // TODO(hhchan): It's 4 in java.  Figure out why even 3 is too slow in prod mode.
    return 2;
  }

  // Use fewer steps in the IteratorTester in CollectionIteratorTester because it's slow in prod
  // mode.
  static int collectionIteratorTesterNumIterations() {
    return 3;
  }

  // TODO: Consolidate different copies in one single place.

import java.util.ListIterator;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A utility similar to {@link IteratorTester} for testing a {@link ListIterator} against a known
 * good reference implementation. As with {@code IteratorTester}, a concrete subclass must provide
 * target iterators on demand. It also requires three additional constructor parameters: {@code

  public void testIterator_oneElement() {
    new IteratorTester<String>(
        5, UNMODIFIABLE, singleton("a"), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<String> newTargetIterator() {
        return of("a").iterator();
      }
    }.test();
  }

  @GwtIncompatible // slow (~30s)
  public void testIterator_general() {
    new IteratorTester<String>(

    assertThrows(UnsupportedOperationException.class, () -> iterator.remove());
  }

  @GwtIncompatible // slow (~35s)
  public void testSkip_iterator() {
    new IteratorTester<Integer>(
        5, MODIFIABLE, newArrayList(2, 3), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<Integer> newTargetIterator() {
        return skip(new LinkedHashSet<>(asList(1, 2, 3)), 1).iterator();
      }

    assertThrows(UnsupportedOperationException.class, () -> iterator.remove());
  }

  @GwtIncompatible // slow (~35s)
  public void testSkip_iterator() {
    new IteratorTester<Integer>(
        5, MODIFIABLE, newArrayList(2, 3), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<Integer> newTargetIterator() {
        return skip(new LinkedHashSet<>(asList(1, 2, 3)), 1).iterator();
      }

 * Unit test for {@code Sets}.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy
 */
@GwtCompatible
@NullMarked
public class SetsTest extends TestCase {

  private static final IteratorTester.KnownOrder KNOWN_ORDER =
      IteratorTester.KnownOrder.KNOWN_ORDER;

  private static final Collection<Integer> EMPTY_COLLECTION = Arrays.<Integer>asList();

  private static final Collection<Integer> SOME_COLLECTION = asList(0, 1, 1);

  }

  private <T extends Comparable<T>> void runIterator(List<T> values, int steps) throws Exception {
    IteratorTester<T> tester =
        new IteratorTester<T>(
            steps,
            IteratorFeature.MODIFIABLE,
            new LinkedList<>(values),
            IteratorTester.KnownOrder.UNKNOWN_ORDER) {
          private @Nullable MinMaxPriorityQueue<T> mmHeap;

          @Override