public void testToString() {
    Set<String> set = of("a", "b", "c", "d", "e", "f", "g");
    assertEquals("[a, b, c, d, e, f, g]", set.toString());
  }

  @GwtIncompatible // slow (~40s)
  public void testIterator_oneElement() {
    new IteratorTester<String>(
        5, UNMODIFIABLE, singleton("a"), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<String> newTargetIterator() {