expectUnchanged();
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_emptyPreviouslyEmptyUnsupported() {
    expectReturnsFalseOrThrows(empty);
    expectUnchanged();
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRetainAll_emptyPreviouslyNonEmpty() {

    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();

  }

  @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)

    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutIfAbsent_unsupportedPresentDifferentValue() {
    try {
      getMap().putIfAbsent(k0(), v3());
    } catch (UnsupportedOperationException tolerated) {
    }
    expectUnchanged();
  }

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

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAtIndex_supportedPresent() {
    getList().add(0, e0());
    expectAdded(0, e0());
  }

  @ListFeature.Require(absent = SUPPORTS_ADD_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  /*
   * absent = ZERO isn't required, since unmodList.add() must

        });
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutAll_unsupportedSomePresent() {
    assertThrows(
        UnsupportedOperationException.class, () -> putAll(MinimalCollection.of(e3(), e0())));
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)

  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testAddAll_unsupportedNonePresent() {
    assertThrows(
        UnsupportedOperationException.class, () -> collection.addAll(createDisjointCollection()));
    expectUnchanged();
    expectMissing(e3(), e4());
  }

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

  @ListFeature.Require(SUPPORTS_SET)
  @CollectionSize.Require(absent = ZERO)
  public void testSet() {
    doTestSet(e3());
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @ListFeature.Require(SUPPORTS_SET)
  public void testSet_null() {
    doTestSet(null);
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)

  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());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutAllNonEmptyIterableOnPresentKey() {
    assertTrue(multimap().putAll(k0(), newArrayList(v3(), v4())::iterator));
    assertGet(k0(), v0(), v3(), v4());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_PUT)