assertEquals(a, navigableSet.pollLast());
    assertTrue(navigableSet.isEmpty());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollFirst() {
    assertEquals(a, navigableSet.pollFirst());
    assertEquals(values.subList(1, values.size()), copyToList(navigableSet));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)

    assertEquals(a, navigableSet.pollLast());
    assertTrue(navigableSet.isEmpty());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollFirst() {
    assertEquals(a, navigableSet.pollFirst());
    assertEquals(values.subList(1, values.size()), copyToList(navigableSet));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)

  @CollectionSize.Require(SEVERAL)
  public void testFirst() {
    assertEquals(a, navigableMap.firstEntry());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollFirst() {
    assertEquals(a, navigableMap.pollFirstEntry());
    assertEquals(entries.subList(1, entries.size()), copyToList(navigableMap.entrySet()));
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)

        assertThat(filtered.descendingSet())
            .containsExactlyElementsIn(unfiltered.descendingSet())
            .inOrder();
      }
    }

    public void testPollFirst() {
      for (List<Integer> contents : SAMPLE_INPUTS) {
        NavigableSet<Integer> filtered = filter(createUnfiltered(contents), EVEN);
        NavigableSet<Integer> unfiltered = createUnfiltered(filtered);

  public void testFirst() {
    assertEquals(a, sortedMultiset.firstEntry());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollFirst() {
    assertEquals(a, sortedMultiset.pollFirstEntry());
    assertEquals(asList(b, c), copyToList(sortedMultiset.entrySet()));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)

  public void testFirst() {
    assertEquals(a, sortedMultiset.firstEntry());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testPollFirst() {
    assertEquals(a, sortedMultiset.pollFirstEntry());
    assertEquals(asList(b, c), copyToList(sortedMultiset.entrySet()));
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)