public static <E> Collection<List<E>> permutations(Collection<E> elements) {
    return new PermutationCollection<E>(ImmutableList.copyOf(elements));
  }

  private static final class PermutationCollection<E> extends AbstractCollection<List<E>> {
    final ImmutableList<E> inputList;

    PermutationCollection(ImmutableList<E> input) {
      this.inputList = input;
    }

    @Override
    public int size() {

  public void testFindClassesToTest_testClass() {
    assertThat(findClassesToTest(ImmutableList.of(EmptyTest.class))).isEmpty();
    assertThat(findClassesToTest(ImmutableList.of(EmptyTests.class))).isEmpty();
    assertThat(findClassesToTest(ImmutableList.of(EmptyTestCase.class))).isEmpty();
    assertThat(findClassesToTest(ImmutableList.of(EmptyTestSuite.class))).isEmpty();
  }

  public void testPutAllNullForbidden() {
    assertThrows(NullPointerException.class, () -> multimap().putAll(null, singletonList(v3())));
  }

  @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types
  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutAllEmptyCollectionOnAbsentKey() {
    assertFalse(multimap().putAll(k3(), Collections.emptyList()));
    expectUnchanged();

  public static <E> Collection<List<E>> permutations(Collection<E> elements) {
    return new PermutationCollection<E>(ImmutableList.copyOf(elements));
  }

  private static final class PermutationCollection<E> extends AbstractCollection<List<E>> {
    final ImmutableList<E> inputList;

    PermutationCollection(ImmutableList<E> input) {
      this.inputList = input;
    }

    @Override
    public int size() {

     * ImmutableSet.copyOf won't short-circuit because it won't see an ImmutableSet input.
     */
    ImmutableList<ImmutableSet<String>> distinctCandidatesByAscendingSize =
        ImmutableList.of(
            ImmutableSet.of(),
            ImmutableSet.of("a"),
            ImmutableSet.of("b", "a"),
            ImmutableSet.of("c", "b", "a"),

    assertEquals(type, returnType.getRawType());
    assertEquals(
        ImmutableList.copyOf(type.getTypeParameters()),
        ImmutableList.copyOf(returnType.getActualTypeArguments()));
  }

  public void testConstructor_exceptionTypes() throws Exception {
    assertEquals(
        ImmutableList.of(TypeToken.of(NullPointerException.class)),

      return this;
    }

    private ImmutableList<Invokable<?, ?>> getFactoriesToTest() {
      ImmutableList.Builder<Invokable<?, ?>> builder = ImmutableList.builder();
      for (Invokable<?, ?> factory : factories) {
        if (returnTypeToTest.isAssignableFrom(factory.getReturnType().getRawType())) {
          builder.add(factory);
        }
      }
      ImmutableList<Invokable<?, ?>> factoriesToTest = builder.build();

    return element.equals(target);
  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return singletonIterator(element);
  }

  @Override
  public ImmutableList<E> asList() {
    return ImmutableList.of(element);
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override
  int copyIntoArray(@Nullable Object[] dst, int offset) {
    dst[offset] = element;

  }

  public void testCreateEmptyWithClass() {
    Multiset<Color> ms = EnumMultiset.create(ImmutableList.<Color>of(), Color.class);
    ms.add(Color.RED);
  }

  public void testCreateEmptyWithoutClassFails() {
    assertThrows(
        IllegalArgumentException.class, () -> EnumMultiset.create(ImmutableList.<Color>of()));
  }

  public void testToString() {

    generator.addSampleInstances(String.class, ImmutableList.of("a"));
    assertThat(generator.generateFresh(String.class)).isEqualTo("a");
    assertThat(generator.generateFresh(String.class)).isEqualTo("a");
  }

  public void testAddSampleInstances_noInstance() {
    FreshValueGenerator generator = new FreshValueGenerator();
    generator.addSampleInstances(String.class, ImmutableList.<String>of());