TopKSelector<Integer> top = TopKSelector.least(10);
    top.offer(3);
    top.offer(5);
    top.offer(2);
    assertThat(top.topK()).containsExactly(2, 3, 5).inOrder();
  }

  public void testOfferedKPlusOne() {
    for (List<Integer> list : Collections2.permutations(Ints.asList(1, 2, 3, 4, 5))) {
      TopKSelector<Integer> top = TopKSelector.least(4);
      top.offerAll(list);