@CollectionFeature.Require(value = KNOWN_ORDER, absent = NON_STANDARD_TOSTRING)
  public void testToString_sizeSeveral() {
    String expected = Helpers.copyToList(getOrderedElements()).toString();
    assertEquals("collection.toString() incorrect", expected, collection.toString());
  }

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

      (11.0 - INTEGER_MANY_VALUES_MEAN) * (11.0 - INTEGER_MANY_VALUES_MEAN)
          + (-22.0 - INTEGER_MANY_VALUES_MEAN) * (-22.0 - INTEGER_MANY_VALUES_MEAN)
          + (3333.0 - INTEGER_MANY_VALUES_MEAN) * (3333.0 - INTEGER_MANY_VALUES_MEAN)
          + (-4444.0 - INTEGER_MANY_VALUES_MEAN) * (-4444.0 - INTEGER_MANY_VALUES_MEAN)

  }

  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  @CollectionSize.Require(absent = ZERO)
  public void testContainsAll_nullPresent() {
    initCollectionWithNullElement();
    assertTrue(collection.containsAll(MinimalCollection.of((E) null)));
  }

  public void testContainsAll_wrongType() {
    Collection<WrongType> wrong = MinimalCollection.of(WrongType.VALUE);
    try {
      assertFalse(

          collection.addAll(MinimalCollection.of(e0())));
    } catch (UnsupportedOperationException tolerated) {
    }
    expectUnchanged();
  }

  @CollectionFeature.Require(
      value = {SUPPORTS_ADD, ALLOWS_NULL_VALUES},
      absent = RESTRICTS_ELEMENTS)
  public void testAddAll_nullSupported() {
    List<E> containsNull = singletonList(null);

              }

              @Override
              public @Nullable String put(String key, String value) {
                checkNotNull(key);
                return map.put(key, value);
              }
            };
          }
        },
        "HashMap w/out null keys",
        ALLOWS_NULL_VALUES);
  }

  private static Test testsForHashMapNullValuesForbidden() {
    return wrappedHashMapTests(

              }

              @Override
              public @Nullable String put(String key, String value) {
                checkNotNull(key);
                return map.put(key, value);
              }
            };
          }
        },
        "HashMap w/out null keys",
        ALLOWS_NULL_VALUES);
  }

  private static Test testsForHashMapNullValuesForbidden() {
    return wrappedHashMapTests(

      for (Integer j : IN_ORDER_VALUES) {
        assertFalse(range.contains(j));
      }
    }
  }

  public void testCreateEmptyRangeOpenClosedSucceeds() {
    for (Integer i : IN_ORDER_VALUES) {
      GeneralRange<@Nullable Integer> range = GeneralRange.range(ORDERING, i, OPEN, i, CLOSED);
      for (Integer j : IN_ORDER_VALUES) {
        assertFalse(range.contains(j));
      }
    }
  }

                }));
    expectAdded(e3());
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testMappedToNull() {
    initMapWithNullValue();
    assertEquals(
        "Map.merge(keyMappedToNull, value, function) should return value",
        v3(),
        getMap()
            .merge(
                getKeyForNullValue(),
                v3(),

              }
            })
        .named("checkedQueue/LinkedList")
        .withFeatures(
            CollectionFeature.GENERAL_PURPOSE,
            CollectionFeature.ALLOWS_NULL_VALUES,
            CollectionFeature.KNOWN_ORDER,
            CollectionFeature.RESTRICTS_ELEMENTS,
            CollectionSize.ANY)

    assertEquals(
        "multiset.remove(wrongType, 1) didn't return 0",
        0,
        getMultiset().remove(WrongType.VALUE, 1));
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  public void testRemove_nullPresent() {
    initCollectionWithNullElement();
    assertEquals(1, getMultiset().remove(null, 2));
    assertFalse(