}

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(absent = NON_STANDARD_TOSTRING)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testToStringWithNullKey() {
    initMapWithNullKey();
    testToString_formatting();
  }

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

    Helpers.assertEqualIgnoringOrder(getSampleEntries(), entries);
  }

  @MapFeature.Require(ALLOWS_NULL_KEYS)
  @CollectionSize.Require(absent = ZERO)
  public void testForEach_nullKeys() {
    initMapWithNullKey();
    List<Entry<K, V>> expectedEntries = asList(createArrayWithNullKey());
    List<Entry<K, V>> entries = new ArrayList<>();
    getMap().forEach((k, v) -> entries.add(entry(k, v)));

    assertFalse(getMap().containsValue(v0()));
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  @CollectionSize.Require(ONE)
  public void testForcePutNullKeyPresent() {
    initMapWithNullKey();

    getMap().forcePut(null, v1());

    expectContents(mapEntry((K) null, v1()));

    assertFalse(getMap().containsValue(v0()));

    assertTrue(getMap().containsValue(v1()));

  }

  @MapFeature.Require({SUPPORTS_PUT, SUPPORTS_REMOVE, ALLOWS_NULL_KEYS})
  @CollectionSize.Require(absent = ZERO)
  public void testCompute_nullKeyPresentToPresent() {
    initMapWithNullKey();
    assertEquals(
        "Map.compute(present, functionReturningValue) should return new value",
        v3(),
        getMap()
            .compute(
                null,
                (k, v) -> {

  }

  @MapFeature.Require({SUPPORTS_PUT, SUPPORTS_REMOVE, ALLOWS_NULL_KEYS})
  @CollectionSize.Require(absent = ZERO)
  public void testCompute_nullKeyPresentToPresent() {
    initMapWithNullKey();
    assertEquals(
        "Map.compute(present, functionReturningValue) should return new value",
        v3(),
        getMap()
            .compute(
                null,
                (k, v) -> {

  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  @CollectionSize.Require(absent = ZERO)
  public void testPut_nullKeySupportedPresent() {
    Entry<K, V> newEntry = entry(null, v3());
    initMapWithNullKey();
    assertEquals(
        "put(present, value) should return the associated value",
        getValueForNullKey(),
        put(newEntry));

    Entry<K, V>[] expected = createArrayWithNullKey();

    expectUnchanged();
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_KEYS})
  @CollectionSize.Require(absent = ZERO)
  public void testComputeIfPresent_nullKeySupportedPresent() {
    initMapWithNullKey();
    assertEquals(
        "computeIfPresent(null, function) should return new value",
        v3(),
        getMap()
            .computeIfPresent(
                null,
                (k, v) -> {

    assertFalse(getMap().entrySet().contains(mapEntry(null, v0())));
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testContainsEntryWithNullKeyPresent() {
    initMapWithNullKey();
    assertTrue(getMap().entrySet().contains(mapEntry(null, getValueForNullKey())));
  }

  @MapFeature.Require(ALLOWS_NULL_VALUE_QUERIES)
  public void testContainsEntryWithNullValueAbsent() {

    assertFalse(getMap().entrySet().contains(mapEntry(null, v0())));
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testContainsEntryWithNullKeyPresent() {
    initMapWithNullKey();
    assertTrue(getMap().entrySet().contains(mapEntry(null, getValueForNullKey())));
  }

  @MapFeature.Require(ALLOWS_NULL_VALUE_QUERIES)
  public void testContainsEntryWithNullValueAbsent() {

    int nullValueLocation = getNullLocation();
    Entry<K, V> oldEntry = array[nullValueLocation];
    array[nullValueLocation] = entry(oldEntry.getKey(), null);
    return array;
  }

  protected void initMapWithNullKey() {
    resetMap(createArrayWithNullKey());
  }

  protected void initMapWithNullValue() {
    resetMap(createArrayWithNullValue());
  }

  /**