// overlap above
    assertEquals(Range.closed(6, 8), range.intersection(Range.closed(6, 10)));

    // adjacent above
    assertEquals(Range.openClosed(8, 8), range.intersection(Range.openClosed(8, 10)));

    // separate above
    expected =
        assertThrows(
            IllegalArgumentException.class, () -> range.intersection(Range.closed(10, 12)));

    assertEquals(set, Sets.subSet(set, Range.openClosed(0, 12)));
    assertEquals(ImmutableSortedSet.of(2, 4), Sets.subSet(set, Range.openClosed(0, 4)));
    assertEquals(ImmutableSortedSet.of(4, 6), Sets.subSet(set, Range.openClosed(2, 6)));
    assertEquals(ImmutableSortedSet.of(4, 6), Sets.subSet(set, Range.openClosed(3, 7)));
    assertEquals(empty, Sets.subSet(set, Range.openClosed(20, 30)));

      if (set.isEmpty()) {
        /*
         * The (tooLow + 1, tooHigh) arguments below would be invalid because tooLow would be
         * greater than tooHigh.
         */
        return ContiguousSet.create(Range.openClosed(0, 1), DiscreteDomain.integers()).subSet(0, 1);
      }
      int tooHigh = set.last() + 1;
      int tooLow = set.first() - 1;
      set.add(tooHigh);
      set.add(tooLow);

      if (set.isEmpty()) {
        /*
         * The (tooLow + 1, tooHigh) arguments below would be invalid because tooLow would be
         * greater than tooHigh.
         */
        return ContiguousSet.create(Range.openClosed(0, 1), DiscreteDomain.integers()).subSet(0, 1);
      }
      int tooHigh = set.last() + 1;
      int tooLow = set.first() - 1;
      set.add(tooHigh);
      set.add(tooLow);