public void testWrap() {
    assertThat(Primitives.wrap(int.class)).isSameInstanceAs(Integer.class);
    assertThat(Primitives.wrap(Integer.class)).isSameInstanceAs(Integer.class);
    assertThat(Primitives.wrap(String.class)).isSameInstanceAs(String.class);
  }

  public void testUnwrap() {
    assertThat(Primitives.unwrap(Integer.class)).isSameInstanceAs(int.class);
    assertThat(Primitives.unwrap(int.class)).isSameInstanceAs(int.class);

   * returns {@code type} itself. Idempotent.
   *
   * <pre>
   *     unwrap(Integer.class) == int.class
   *     unwrap(int.class) == int.class
   *     unwrap(String.class) == String.class
   * </pre>
   */
  public static <T> Class<T> unwrap(Class<T> type) {
    checkNotNull(type);

    // cast is safe: long.class and Long.class are both of type Class<Long>

   * this} itself. Idempotent.
   *
   * @since 15.0
   */
  public final TypeToken<T> unwrap() {
    if (isWrapper()) {
      @SuppressWarnings("unchecked") // this is a wrapper class
      Class<T> type = (Class<T>) runtimeType;
      return of(Primitives.unwrap(type));
    }
    return this;
  }

  /**

  public void testWrap() {
    assertThat(Primitives.wrap(int.class)).isSameInstanceAs(Integer.class);
    assertThat(Primitives.wrap(Integer.class)).isSameInstanceAs(Integer.class);
    assertThat(Primitives.wrap(String.class)).isSameInstanceAs(String.class);
  }

  public void testUnwrap() {
    assertThat(Primitives.unwrap(Integer.class)).isSameInstanceAs(int.class);
    assertThat(Primitives.unwrap(int.class)).isSameInstanceAs(int.class);

      return (enumConstants == null || enumConstants.length == 0) ? null : enumConstants[0];
    }
    if (type.isArray()) {
      return createEmptyArray(type);
    }
    T jvmDefault = Defaults.defaultValue(Primitives.unwrap(type));
    if (jvmDefault != null) {
      return jvmDefault;
    }
    if (Modifier.isAbstract(type.getModifiers()) || !Modifier.isPublic(type.getModifiers())) {
      return arbitraryConstantInstanceOrNull(type);

      return (enumConstants == null || enumConstants.length == 0) ? null : enumConstants[0];
    }
    if (type.isArray()) {
      return createEmptyArray(type);
    }
    T jvmDefault = Defaults.defaultValue(Primitives.unwrap(type));
    if (jvmDefault != null) {
      return jvmDefault;
    }
    if (Modifier.isAbstract(type.getModifiers()) || !Modifier.isPublic(type.getModifiers())) {
      return arbitraryConstantInstanceOrNull(type);

    assertEquals(TypeToken.of(Primitives.wrap((Class<?>) type.getType())), type.wrap());
  }

  private static void assertNotPrimitive(TypeToken<?> type) {
    assertFalse(type.isPrimitive());
    assertSame(type, type.wrap());
  }

  private static void assertIsWrapper(TypeToken<?> type) {
    assertNotPrimitive(type);
    assertEquals(TypeToken.of(Primitives.unwrap((Class<?>) type.getType())), type.unwrap());
  }

   * method wraps the elements in the input sets (which may contain null) as Optionals, calls
   * Sets.cartesianProduct with those, then transforms the result to unwrap the Optionals.
   */
  private Iterable<List<Object>> buildCartesianProduct(Set<?>... sets) {
    List<Set<Optional<?>>> optionalSets = Lists.newArrayListWithExpectedSize(sets.length);
    for (Set<?> set : sets) {

   * method wraps the elements in the input sets (which may contain null) as Optionals, calls
   * Sets.cartesianProduct with those, then transforms the result to unwrap the Optionals.
   */
  private Iterable<List<Object>> buildCartesianProduct(Set<?>... sets) {
    List<Set<Optional<?>>> optionalSets = Lists.newArrayListWithExpectedSize(sets.length);
    for (Set<?> set : sets) {

     */
    runConcurrentlyMutatedTest(elements(), ops(add(1), add(2)), wrap);

    runConcurrentlyMutatedTest(elements(), ops(add(1), nop()), wrap);

    runConcurrentlyMutatedTest(elements(), ops(add(1), remove()), wrap);

    runConcurrentlyMutatedTest(elements(), ops(nop(), add(1)), wrap);

    runConcurrentlyMutatedTest(elements(1), ops(remove(), nop()), wrap);

    runConcurrentlyMutatedTest(elements(1), ops(remove(), add(2)), wrap);