ImmutableSortedSet<String> sortedSet = zis.combine(zat).build();
    assertThat(sortedSet).containsExactly("a", "bb", "ccc", "dddd").inOrder();
  }

  public void testEquals_bothDefaultOrdering() {
    SortedSet<String> set = of("a", "b", "c");
    assertEquals(set, Sets.newTreeSet(asList("a", "b", "c")));
    assertEquals(Sets.newTreeSet(asList("a", "b", "c")), set);

    TypeWithDuplicates c = new TypeWithDuplicates(3, 1);
    CollectorTester.of(collector, equivalence)
        .expectCollects(ImmutableSortedSet.of(a, b1, c), a, b1, c, b2);
  }

  public void testEquals_bothDefaultOrdering() {
    SortedSet<String> set = of("a", "b", "c");
    assertEquals(set, Sets.newTreeSet(asList("a", "b", "c")));
    assertEquals(Sets.newTreeSet(asList("a", "b", "c")), set);