* the call to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
   *
   * @param message message to use upon assertion failure
   */
  protected void expectNullKeyMissingWhenNullKeysUnsupported(String message) {
    try {
      assertFalse(message, getMap().containsKey(null));
    } catch (NullPointerException tolerated) {

   * the call to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
   *
   * @param message message to use upon assertion failure
   */
  protected void expectNullKeyMissingWhenNullKeysUnsupported(String message) {
    try {
      assertFalse(message, getMap().containsKey(null));
    } catch (NullPointerException tolerated) {

@IgnoreJRERequirement // Users will use this only if they're already using Spliterator.
public final class SpliteratorTester<E extends @Nullable Object> {
  /** Return type from "contains the following elements" assertions. */
  public interface Ordered {
    /**
     * Attests that the expected values must not just be present but must be present in the order
     * they were given.
     */
    void inOrder();
  }

 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class SpliteratorTester<E extends @Nullable Object> {
  /** Return type from "contains the following elements" assertions. */
  public interface Ordered {
    /**
     * Attests that the expected values must not just be present but must be present in the order
     * they were given.
     */
    void inOrder();
  }

  }

  /**
   * Asserts that the collection under test contains exactly the given elements, respecting
   * cardinality but not order. Subclasses may override this method to provide stronger assertions,
   * e.g., to check ordering in lists, but realize that <strong>unless a test extends {@link
   * com.google.common.collect.testing.testers.AbstractListTester AbstractListTester}, a call to

    return "z";
  }

  @Override
  protected String getValueNotInPopulatedMap() throws UnsupportedOperationException {
    return "26";
  }

  /** Helper assertion comparing two maps */
  private void assertMapsEqual(Map<?, ?> expected, Map<?, ?> map) {
    assertEquals(expected, map);
    assertEquals(expected.hashCode(), map.hashCode());

    return "z";
  }

  @Override
  protected String getValueNotInPopulatedMap() throws UnsupportedOperationException {
    return "26";
  }

  /** Helper assertion comparing two maps */
  private void assertMapsEqual(Map<?, ?> expected, Map<?, ?> map) {
    assertEquals(expected, map);
    assertEquals(expected.hashCode(), map.hashCode());

 *
 * @param <K> the type of keys used by the maps under test
 * @param <V> the type of mapped values used the maps under test
 * @author George van den Driessche
 */
// TODO: Descriptive assertion messages, with hints as to probable fixes.
// TODO: Add another constructor parameter indicating whether the class under test is ordered, and
// check the order if so.
// TODO: Refactor to share code with SetTestBuilder etc.

 *
 * @param <K> the type of keys used by the maps under test
 * @param <V> the type of mapped values used the maps under test
 * @author George van den Driessche
 */
// TODO: Descriptive assertion messages, with hints as to probable fixes.
// TODO: Add another constructor parameter indicating whether the class under test is ordered, and
// check the order if so.
// TODO: Refactor to share code with SetTestBuilder etc.

     * iterator's next element and pass it to the reference iterator through this method so it can
     * return the same element. This enables the assertion to pass and the reference iterator to
     * properly update its state.
     */
    void promoteToNext(E e) {
      if (nextElements.remove(e)) {
        nextElements.push(e);
      } else {