var with, withOut nErr
	with.n, with.err = io.Copy(discard, NewReader(nil))
	withOut.n, withOut.err = io.Copy(discard, justReader{NewReader(nil)})
	if with != withOut {
		t.Errorf("behavior differs: with = %#v; without: %#v", with, withOut)
	}
}

// tests that Len is affected by reads, but Size is not.
func TestReaderLenSize(t *testing.T) {
	r := NewReader([]byte("abc"))
	io.CopyN(io.Discard, r, 1)
	if r.Len() != 2 {

 * you should use the non-mutating {@link Graph} interface, or an {@link ImmutableGraph}.
 *
 * <p>You can create an immutable copy of an existing {@code Graph} using {@link
 * ImmutableGraph#copyOf(Graph)}:
 *
 * {@snippet :
 * ImmutableGraph<Integer> immutableGraph = ImmutableGraph.copyOf(graph);
 * }
 *
 * <p>Instances of {@link ImmutableGraph} do not implement {@link MutableGraph} (obviously!) and are

 * you should use the non-mutating {@link Graph} interface, or an {@link ImmutableGraph}.
 *
 * <p>You can create an immutable copy of an existing {@code Graph} using {@link
 * ImmutableGraph#copyOf(Graph)}:
 *
 * {@snippet :
 * ImmutableGraph<Integer> immutableGraph = ImmutableGraph.copyOf(graph);
 * }
 *
 * <p>Instances of {@link ImmutableGraph} do not implement {@link MutableGraph} (obviously!) and are

   *     array}, plus {@code element} occupying the last position.
   */
  public static <T extends @Nullable Object> T[] concat(T[] array, @ParametricNullness T element) {
    T[] result = Arrays.copyOf(array, array.length + 1);
    result[array.length] = element;
    return result;
  }

  /**
   * Returns an array containing all of the elements in the specified collection; the runtime type

      setSucceeds(dstIndex, getSuccessor(srcIndex));
    }
    setLink(srcIndex, 0);
  }

  @Override
  void resizeEntries(int newCapacity) {
    super.resizeEntries(newCapacity);
    links = Arrays.copyOf(requireLinks(), newCapacity);
  }

  @Override
  int firstEntryIndex() {
    return firstEntry;
  }

  @Override
  int adjustAfterRemove(int indexBeforeRemove, int indexRemoved) {

    for (int i = 0; i < 3; i++) {
      assertEquals(i + 1, list.get(i).intValue());
    }
    assertEquals(ImmutableList.of(1, 2, 3), ImmutableList.copyOf(list.iterator()));
    assertEquals(ImmutableList.of(1, 2, 3), ImmutableList.copyOf(list.toArray(new Integer[0])));
  }

  @J2ktIncompatible
  @GwtIncompatible // suite
  @AndroidIncompatible // test-suite builders

   *     array}, plus {@code element} occupying the last position.
   */
  public static <T extends @Nullable Object> T[] concat(T[] array, @ParametricNullness T element) {
    T[] result = Arrays.copyOf(array, array.length + 1);
    result[array.length] = element;
    return result;
  }

  /**
   * Returns an array containing all of the elements in the specified collection; the runtime type

              public Collection<String> create(String[] elements) {
                List<String> unfiltered = new ArrayList<>();
                unfiltered.add("yyy");
                unfiltered.addAll(ImmutableList.copyOf(elements));
                unfiltered.add("zzz");
                return Collections2.filter(unfiltered, LENGTH_1);
              }
            })
        .named("Collections2.filter, no nulls")

 * ImmutableValueGraph}.
 *
 * <p>You can create an immutable copy of an existing {@code ValueGraph} using {@link
 * ImmutableValueGraph#copyOf(ValueGraph)}:
 *
 * {@snippet :
 * ImmutableValueGraph<Integer, Double> immutableGraph = ImmutableValueGraph.copyOf(graph);
 * }
 *
 * <p>Instances of {@link ImmutableValueGraph} do not implement {@link MutableValueGraph}

              @Override
              public Set<AnEnum> create(AnEnum[] elements) {
                return (elements.length == 0)
                    ? EnumSet.noneOf(AnEnum.class)
                    : EnumSet.copyOf(MinimalCollection.of(elements));
              }
            })
        .named("EnumSet")
        .withFeatures(
            SetFeature.GENERAL_PURPOSE,
            CollectionFeature.SERIALIZABLE,