ImmutableSet<String> copy = ImmutableSet.copyOf(sortedSet);
    assertThat(copy).isNotSameInstanceAs(sortedSet);
  }

  // TODO(b/172823566): Use mainline testToImmutableSet once CollectorTester is usable to java7.
  public void testToImmutableSet_java7() {
    ImmutableSet.Builder<String> zis = ImmutableSet.<String>builder().add("a", "b", "a");

    ImmutableSortedSet<String> sortedSet = ImmutableSortedSet.of("a");
    ImmutableSet<String> copy = ImmutableSet.copyOf(sortedSet);
    assertThat(copy).isNotSameInstanceAs(sortedSet);
  }

  public void testToImmutableSet() {
    Collector<String, ?, ImmutableSet<String>> collector = toImmutableSet();
    Equivalence<ImmutableSet<String>> equivalence =
        Equivalence.equals().onResultOf(ImmutableSet::asList);