assertFalse(iter.hasNext());
  }

  public void testAsEnumerationEmpty() {
    Iterator<Integer> iter = Iterators.emptyIterator();
    Enumeration<Integer> enumer = Iterators.asEnumeration(iter);

    assertFalse(enumer.hasMoreElements());
    try {
      enumer.nextElement();
      fail();
    } catch (NoSuchElementException expected) {
    }
  }

    assertFalse(iter.hasNext());
  }

  public void testAsEnumerationEmpty() {
    Iterator<Integer> iter = Iterators.emptyIterator();
    Enumeration<Integer> enumer = Iterators.asEnumeration(iter);

    assertFalse(enumer.hasMoreElements());
    try {
      enumer.nextElement();
      fail();
    } catch (NoSuchElementException expected) {
    }
  }

   *
   * <p>The {@code Iterable} equivalent of this method is either {@link Collections#enumeration} (if
   * you have a {@link Collection}), or {@code Iterators.asEnumeration(collection.iterator())}.
   */
  public static <T extends @Nullable Object> Enumeration<T> asEnumeration(Iterator<T> iterator) {
    checkNotNull(iterator);
    return new Enumeration<T>() {
      @Override
      public boolean hasMoreElements() {

   *
   * <p>The {@code Iterable} equivalent of this method is either {@link Collections#enumeration} (if
   * you have a {@link Collection}), or {@code Iterators.asEnumeration(collection.iterator())}.
   */
  public static <T extends @Nullable Object> Enumeration<T> asEnumeration(Iterator<T> iterator) {
    checkNotNull(iterator);
    return new Enumeration<T>() {
      @Override
      public boolean hasMoreElements() {

  public void testFromPropertiesNullKey() {
    Properties properties =
        new Properties() {
          @Override
          public Enumeration<?> propertyNames() {
            return Iterators.asEnumeration(Arrays.asList(null, "first", "second").iterator());
          }
        };
    properties.setProperty("first", "true");
    properties.setProperty("second", "null");

    try {

  public void testFromPropertiesNullKey() {
    Properties properties =
        new Properties() {
          @Override
          public Enumeration<?> propertyNames() {
            return Iterators.asEnumeration(Arrays.asList(null, "first", "second").iterator());
          }
        };
    properties.setProperty("first", "true");
    properties.setProperty("second", "null");

    try {