v3(),
                (oldV, newV) -> {
                  assertEquals(v0(), oldV);
                  assertEquals(v3(), newV);
                  return null;
                }));
    expectMissing(e0());
  }

  public void testMergeNullValue() {
    try {
      getMap()
          .merge(
              k0(),
              null,
              (oldV, newV) -> {

    try {
      put(e3());
      fail("put(notPresent, value) should throw");
    } catch (UnsupportedOperationException expected) {
    }
    expectUnchanged();
    expectMissing(e3());
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPut_unsupportedPresentExistingValue() {
    try {

   * AbstractListTester isn't enough because many tests that run on lists don't
   * extends AbstractListTester.) We could also iterate over all elements to
   * verify absence
   */
  protected void expectMissing(E... elements) {
    for (E element : elements) {
      assertFalse("Should not contain " + element, actualContents().contains(element));
    }
  }

  protected E[] createSamplesArray() {

    try {
      putAll(createDisjointCollection());
      fail("putAll(nonePresent) should throw");
    } catch (UnsupportedOperationException expected) {
    }
    expectUnchanged();
    expectMissing(e3(), e4());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutAll_supportedSomePresent() {
    putAll(MinimalCollection.of(e3(), e0()));

    return getSampleElements(howMany);
  }

  protected Collection<Entry<K, V>> getSampleEntries() {
    return getSampleElements();
  }

  @Override
  protected void expectMissing(Entry<K, V>... entries) {
    for (Entry<K, V> entry : entries) {
      assertFalse("Should not contain entry " + entry, actualContents().contains(entry));
      assertFalse(

    try {
      collection.addAll(createDisjointCollection());
      fail("addAll(nonePresent) should throw");
    } catch (UnsupportedOperationException expected) {
    }
    expectUnchanged();
    expectMissing(e3(), e4());
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAll_supportedSomePresent() {
    assertTrue(

    try {
      collection.addAll(createDisjointCollection());
      fail("addAll(nonePresent) should throw");
    } catch (UnsupportedOperationException expected) {
    }
    expectUnchanged();
    expectMissing(e3(), e4());
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAll_supportedSomePresent() {
    assertTrue(

    return getSampleElements(howMany);
  }

  protected Collection<Entry<K, V>> getSampleEntries() {
    return getSampleElements();
  }

  @Override
  protected void expectMissing(Entry<K, V>... entries) {
    for (Entry<K, V> entry : entries) {
      assertFalse("Should not contain entry " + entry, actualContents().contains(entry));
      assertFalse(

   * AbstractListTester isn't enough because many tests that run on lists don't
   * extends AbstractListTester.) We could also iterate over all elements to
   * verify absence
   */
  protected void expectMissing(E... elements) {
    for (E element : elements) {
      assertFalse("Should not contain " + element, actualContents().contains(element));
    }
  }

  protected E[] createSamplesArray() {

    try {
      put(e3());
      fail("put(notPresent, value) should throw");
    } catch (UnsupportedOperationException expected) {
    }
    expectUnchanged();
    expectMissing(e3());
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPut_unsupportedPresentExistingValue() {
    try {