public void testAbsent() {
    assertEquals(
        "Map.merge(absent, value, function) should return value",
        v3(),
        getMap()
            .merge(
                k3(),
                v3(),
                (oldV, newV) -> {
                  throw new AssertionFailedError(
                      "Should not call merge function if key was absent");
                }));
    expectAdded(e3());
  }

    Set<Object> absentAsSet = Optional.absent().asSet();
    assertThrows(UnsupportedOperationException.class, () -> absentAsSet.add("foo"));
  }

  public void testTransform_absent() {
    assertEquals(Optional.absent(), Optional.absent().transform(Functions.identity()));
    assertEquals(Optional.absent(), Optional.absent().transform(Functions.toStringFunction()));
  }

    }
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemove_unsupportedPresent() {
    assertThrows(UnsupportedOperationException.class, () -> getMap().remove(k0(), v0()));
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  public void testRemove_unsupportedAbsent() {
    try {

    }
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemove_unsupportedPresent() {
    assertThrows(UnsupportedOperationException.class, () -> getMap().remove(k0(), v0()));
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  public void testRemove_unsupportedAbsent() {
    try {

    assertOneToOne();
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testSetCount_oneToOne_removeSupported() {
    assertOneToOne();
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(absent = {SUPPORTS_ADD, SUPPORTS_REMOVE})
  public void testSetCount_oneToOne_unsupported() {
    try {
      assertOneToOne();

    assertEquals("multiset.count(null) didn't return 0", 0, getMultiset().count(null));
  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_QUERIES)
  public void testCount_null_forbidden() {
    assertThrows(NullPointerException.class, () -> getMultiset().count(null));
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testCount_nullPresent() {

    nextInBucketVToK[src] = ABSENT;
  }

  @Override
  public void clear() {
    Arrays.fill(keys, 0, size, null);
    Arrays.fill(values, 0, size, null);
    Arrays.fill(hashTableKToV, ABSENT);
    Arrays.fill(hashTableVToK, ABSENT);
    Arrays.fill(nextInBucketKToV, 0, size, ABSENT);
    Arrays.fill(nextInBucketVToK, 0, size, ABSENT);
    Arrays.fill(prevInInsertionOrder, 0, size, ABSENT);

  @CollectionSize.Require(absent = ZERO)
  public void testReplaceEntry_presentNullValueUnsupported() {
    assertThrows(NullPointerException.class, () -> getMap().replace(k0(), v0(), null));
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_VALUE_QUERIES)
  @CollectionSize.Require(absent = ZERO)

  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPut_unsupportedPresentExistingValue() {
    try {
      assertEquals("put(present, existingValue) should return present or throw", v0(), put(e0()));
    } catch (UnsupportedOperationException tolerated) {
    }
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)

  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemove_unsupported() {
    assertThrows(UnsupportedOperationException.class, () -> getMap().remove(k0()));
    expectUnchanged();
    assertEquals("remove(present) should not remove the element", v0(), get(k0()));
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)