this.allowsNullKeys = allowsNullKeys;
    this.allowsNullValues = allowsNullValues;
    this.supportsIteratorRemove = supportsIteratorRemove;
  }

  /**
   * Used by tests that require a map, but don't care whether it's populated or not.
   *
   * @return a new map instance.
   */
  protected Map<K, V> makeEitherMap() {
    try {
      return makePopulatedMap();
    } catch (UnsupportedOperationException e) {

    try {
      builder.buildOrThrow();
      fail("Expected exception from duplicate keys");
    } catch (IllegalArgumentException expected) {
      // We don't really care which values the exception message contains, but they should be
      // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
      // not being true.

    public int available() throws IOException {
      return (int) Math.min(in.available(), left);
    }

    // it's okay to mark even if mark isn't supported, as reset won't work
    @Override
    public synchronized void mark(int readLimit) {
      in.mark(readLimit);
      mark = left;
    }

    @Override
    public int read() throws IOException {
      if (left == 0) {
        return -1;
      }

         * protect ourselves from this, we park ourselves and tell our interrupter that we did so.
         */
        if (state == PARKED || compareAndSet(state, PARKED)) {
          // Interrupting Cow Says:
          //  ______
          // < Park >
          //  ------
          //        \   ^__^
          //         \  (oo)\_______

    assertEquals(big[1], small[3]);
  }

  public void testLimit_mark() throws Exception {
    byte[] big = newPreFilledByteArray(5);
    InputStream bin = new ByteArrayInputStream(big);
    InputStream lin = ByteStreams.limit(bin, 2);

    int read = lin.read();
    assertEquals(big[0], read);
    lin.mark(2);

    read = lin.read();
    assertEquals(big[1], read);
    read = lin.read();

  }

  public void testCheckElementIndex_badSize() {
    try {
      Preconditions.checkElementIndex(1, -1);
      fail();
    } catch (IllegalArgumentException expected) {
      // don't care what the message text is, as this is an invalid usage of
      // the Preconditions class, unlike all the other exceptions it throws
    }
  }

  public void testCheckElementIndex_negative() {
    try {

    for (int i = 0; i < 50; i++) {
      list.add(new Object());
    }

    Ordering<Object> arbitrary = Ordering.arbitrary();
    Collections.sort(list, arbitrary);

    // Now we don't care what order it's put the list in, only that
    // comparing any pair of elements gives the answer we expect.
    Helpers.testComparator(arbitrary, list);

    assertEquals("Ordering.arbitrary()", arbitrary.toString());

    for (int i = 0; i < 50; i++) {
      list.add(new Object());
    }

    Ordering<Object> arbitrary = Ordering.arbitrary();
    Collections.sort(list, arbitrary);

    // Now we don't care what order it's put the list in, only that
    // comparing any pair of elements gives the answer we expect.
    Helpers.testComparator(arbitrary, list);

    assertEquals("Ordering.arbitrary()", arbitrary.toString());

   * exercise null handling fail on those subcollections.
   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*
     * We don't serialize this class in GWT, so we don't care about whether GWT will serialize this
     * field.
     */
    @GwtTransient private final String justAfterNull;

    protected NullsBefore(String justAfterNull) {
      if (justAfterNull == null) {

                            "b", (Collection<String>) ImmutableSortedSet.of("bob", "bagel")),
                        Helpers.mapEntry(
                            "c", (Collection<String>) ImmutableSortedSet.of("carl", "carol")),
                        Helpers.mapEntry(
                            "d", (Collection<String>) ImmutableSortedSet.of("david", "dead")),
                        Helpers.mapEntry(