assertTrue(copy instanceof ImmutableEnumSet);
  }

  public void testImmutableEnumSet_fromIterable() {
    ImmutableSet<SomeEnum> none = Sets.immutableEnumSet(MinimalIterable.<SomeEnum>of());
    assertThat(none).isEmpty();

    ImmutableSet<SomeEnum> one = Sets.immutableEnumSet(MinimalIterable.of(SomeEnum.B));
    assertThat(one).contains(SomeEnum.B);