@CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemove_present() {
    getSet().remove(e0());
    assertFalse(
        "After remove(present) a set should not contain the removed element.",
        getSet().contains(e0()));
  }

  public void testIndexOf_duplicate() {
    E[] array = createSamplesArray();
    array[getNumElements() / 2] = e0();
    collection = getSubjectGenerator().create(array);
    assertEquals(
        "indexOf(duplicate) should return index of first occurrence", 0, getList().indexOf(e0()));
  }

  public void testPeek_size1() {
    assertEquals("size1Queue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

  @CollectionFeature.Require(KNOWN_ORDER)
  @CollectionSize.Require(SEVERAL)
  public void testPeek_sizeMany() {
    assertEquals("sizeManyQueue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

  public void testCount_1() {
    assertEquals("multiset.count(present) didn't return 1", 1, getMultiset().count(e0()));
  }

  @CollectionSize.Require(SEVERAL)
  public void testCount_3() {
    initThreeCopies();
    assertEquals("multiset.count(thriceContained) didn't return 3", 3, getMultiset().count(e0()));
  }

  @CollectionFeature.Require(ALLOWS_NULL_QUERIES)
  public void testCount_nullAbsent() {

          putAll(MinimalCollection.of(e3(), e0()));
          iterator.next();
        });
  }

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

  public void testSingletonMultisetNearby() {
    assertNull(sortedMultiset.headMultiset(e0(), OPEN).lastEntry());
    assertNull(sortedMultiset.tailMultiset(e0(), OPEN).lastEntry());

    assertEquals(a, sortedMultiset.headMultiset(e0(), CLOSED).lastEntry());
    assertEquals(a, sortedMultiset.tailMultiset(e0(), CLOSED).firstEntry());
  }

  @CollectionSize.Require(ONE)
  public void testSingletonMultisetLast() {

  @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

  public void testPutWithSameValueFails() {
    getMap().put(k0(), v0());
    assertThrows(IllegalArgumentException.class, () -> getMap().put(k1(), v0()));
    // verify that the bimap is unchanged
    expectAdded(e0());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(ZERO)
  public void testPutPresentKeyDifferentValue() {
    getMap().put(k0(), v0());
    getMap().put(k0(), v1());

  public void testPeek_size1() {
    assertEquals("size1Queue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

  @CollectionFeature.Require(KNOWN_ORDER)
  @CollectionSize.Require(SEVERAL)
  public void testPeek_sizeMany() {
    assertEquals("sizeManyQueue.peek() should return first element", e0(), getQueue().peek());
    expectUnchanged();
  }

  public void testElement_size1() {
    assertEquals("size1Queue.element() should return first element", e0(), getQueue().element());
    expectUnchanged();
  }

  @CollectionFeature.Require(KNOWN_ORDER)
  @CollectionSize.Require(SEVERAL)
  public void testElement_sizeMany() {
    assertEquals("sizeManyQueue.element() should return first element", e0(), getQueue().element());
    expectUnchanged();
  }