assertThat(rangeSet.complement().asRanges())
        .containsExactly(Range.lessThan(3), Range.greaterThan(3))
        .inOrder();
  }

  public void testRemoveMiddle() {
    TreeRangeSet<Integer> rangeSet = TreeRangeSet.create();
    rangeSet.add(Range.atMost(6));
    rangeSet.remove(Range.closedOpen(3, 4));
    testInvariants(rangeSet);
    assertThat(rangeSet.asRanges())