}

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_nullContained() {
    initMapWithNullKey();
    assertTrue("containsKey(null) should return true", getMap().containsKey(null));
  }

  @MapFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContains_keyWithNullValueContained() {

  @MapFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(SEVERAL)
  public void testMultimapRemoveDeletesFirstOccurrence() {
    resetContainer(mapEntry(k0(), v0()), mapEntry(k0(), v1()), mapEntry(k0(), v0()));

    List<V> list = multimap().get(k0());
    multimap().remove(k0(), v0());
    assertContentsInOrder(list, v1(), v0());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)

                  throw new AssertionFailedError(
                      "Should not call merge function if key was absent");
                }));
    expectAdded(e3());
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testMappedToNull() {
    initMapWithNullValue();
    assertEquals(
        "Map.merge(keyMappedToNull, value, function) should return value",
        v3(),

  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testEmptyMultisetPollLast() {
    assertNull(sortedMultiset.pollLastEntry());
  }

  @CollectionSize.Require(ONE)
  public void testSingletonMultisetFirst() {
    assertEquals(a, sortedMultiset.firstEntry());
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ONE)

  }

  @MapFeature.Require(absent = ALLOWS_NULL_KEY_QUERIES)
  public void testGet_nullNotContainedAndUnsupported() {
    try {
      assertNull("get(null) should return null or throw", get(null));
    } catch (NullPointerException tolerated) {
    }
  }

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testGet_nonNullWhenNullContained() {

  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(SEVERAL)
  public void testSetValue_valuePresent() {
    for (Entry<K, V> entry : getMap().entrySet()) {
      if (entry.getKey().equals(k0())) {
        assertThrows(IllegalArgumentException.class, () -> entry.setValue(v1()));
      }
    }
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_VALUES)

    assertEquals("Different ordered iteration", expected, iteratorElements);
  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testIterator_nullElement() {
    initCollectionWithNullElement();
    List<E> iteratorElements = new ArrayList<>();
    for (E element : collection) { // uses iterator()
      iteratorElements.add(element);
    }

public class BiMapClearTester<K, V> extends AbstractBiMapTester<K, V> {
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();
    getMap().clear();
    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testKeySetClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();

public class QueuePollTester<E> extends AbstractQueueTester<E> {
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testPoll_empty() {
    assertNull("emptyQueue.poll() should return null", getQueue().poll());
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ONE)
  public void testPoll_size1() {

        keys.entrySet(), Multisets.immutableEntry(k0(), 2), Multisets.immutableEntry(k1(), 1));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)
  public void testKeysCountAbsentNullKey() {
    assertEquals(0, multimap().keys().count(null));
  }

  @CollectionSize.Require(SEVERAL)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testKeysWithNullKey() {