"A Set should not equal another Set containing different elements.",
        getSet().equals(MinimalSet.from(elements)));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testEquals_containingNull() {
    Collection<E> elements = getSampleElements(getNumElements() - 1);
    elements.add(null);

    collection = getSubjectGenerator().create(elements.toArray());

  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testSpliteratorNullable() {
    initCollectionWithNullElement();
    assertFalse(collection.spliterator().hasCharacteristics(Spliterator.NONNULL));
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testSpliteratorNotImmutable_collectionAllowsAdd() {
    // If add is supported, verify that IMMUTABLE is not reported.

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public class MultisetIteratorTester<E extends @Nullable Object> extends AbstractMultisetTester<E> {
  @CollectionFeature.Require({SUPPORTS_ITERATOR_REMOVE, KNOWN_ORDER})
  public void testRemovingIteratorKnownOrder() {
    new IteratorTester<E>(
        4,
        MODIFIABLE,
        getSubjectGenerator().order(asList(e0(), e1(), e1(), e2())),

    extends AbstractMultimapTester<K, V, Multimap<K, V>> {
  @CollectionSize.Require(absent = ZERO)
  public void testContainsValueYes() {
    assertTrue(multimap().containsValue(v0()));
  }

  public void testContainsValueNo() {
    assertFalse(multimap().containsValue(v3()));
  }

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

public class SetAddAllTester<E> extends AbstractSetTester<E> {
  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAll_supportedSomePresent() {
    assertTrue(
        "add(somePresent) should return true", getSet().addAll(MinimalCollection.of(e3(), e0())));
    expectAdded(e3());
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddAll_withDuplicates() {

  @CollectionFeature.Require(SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  public void testAddAll_supportedAllPresent() {
    assertTrue(
        "addAll(allPresent) should return true", getList().addAll(MinimalCollection.of(e0())));
    expectAdded(e0());
  }

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

  }

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

  return null
}

internal fun Headers.Builder.commonBuild(): Headers = Headers(namesAndValues.toTypedArray())

internal fun headersCheckName(name: String) {
  require(name.isNotEmpty()) { "name is empty" }
  for (i in name.indices) {
    val c = name[i]
    require(c in '\u0021'..'\u007e') {
      "Unexpected char 0x${c.charCode()} at $i in header name: $name"
    }
  }
}

internal fun headersCheckValue(

  // Tests for non-duplicate values are in MultimapPutTester

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutDuplicateValuePreservesSize() {
    assertFalse(multimap().put(k0(), v0()));
    assertEquals(getNumElements(), multimap().size());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutDuplicateValue() {

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @ListFeature.Require(absent = {SUPPORTS_SET, SUPPORTS_ADD_WITH_INDEX})
  public void testListIterator_unmodifiable() {
    runListIteratorTest(UNMODIFIABLE);
  }

  /*
   * For now, we don't cope with testing this when the list supports only some
   * modification operations.
   */
  @CollectionFeature.Require(SUPPORTS_REMOVE)