if n := len(cmap.Comments()); n != len(f.Comments) {
		t.Errorf("got %d comment groups in map; want %d", n, len(f.Comments))
	}

	// support code to update test:
	// set genMap to true to generate res map
	const genMap = false
	if genMap {
		out := make([]string, 0, len(cmap))
		for n, list := range cmap {
			out = append(out, fmt.Sprintf("\t\"%2d: %T\":\t%q,", fset.Position(n.Pos()).Line, n, ctext(list)))
		}

	if err != nil {
		panic(err)
	}
	jsonBig = b
}

func genValue(n int) any {
	if n > 1 {
		switch rand.Intn(2) {
		case 0:
			return genArray(n)
		case 1:
			return genMap(n)
		}
	}
	switch rand.Intn(3) {
	case 0:
		return rand.Intn(2) == 0
	case 1:
		return rand.NormFloat64()
	case 2:
		return genString(30)
	}
	panic("unreachable")
}

    getMap().forcePut(k1(), null);

    expectContents(Helpers.mapEntry(k1(), (V) null));

    assertFalse(getMap().containsKey(k0()));

    assertTrue(getMap().containsKey(k1()));
    assertTrue(getMap().inverse().containsKey(null));
    assertNull(getMap().get(k1()));
    assertEquals(k1(), getMap().inverse().get(null));
    assertEquals(1, getMap().size());
  }

    getMap().forcePut(k1(), null);

    expectContents(Helpers.mapEntry(k1(), (V) null));

    assertFalse(getMap().containsKey(k0()));

    assertTrue(getMap().containsKey(k1()));
    assertTrue(getMap().inverse().containsKey(null));
    assertNull(getMap().get(k1()));
    assertEquals(k1(), getMap().inverse().get(null));
    assertEquals(1, getMap().size());
  }

  @CollectionSize.Require(absent = ZERO)
  public void testRemove_present() {
    int initialSize = getMap().size();
    assertEquals("remove(present) should return the associated value", v0(), getMap().remove(k0()));
    assertEquals(
        "remove(present) should decrease a map's size by one.", initialSize - 1, getMap().size());
    expectMissing(e0());
  }

  public void testKeySetIteratorRemove() {
    int initialSize = getNumElements();
    Iterator<K> iterator = getMap().keySet().iterator();
    iterator.next();
    iterator.remove();
    assertEquals(initialSize - 1, getMap().size());
    assertEquals(initialSize - 1, getMap().inverse().size());
  }

public class ConcurrentMapReplaceTester<K, V> extends AbstractMapTester<K, V> {
  @Override
  protected ConcurrentMap<K, V> getMap() {
    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplace_supportedPresent() {
    assertEquals(v0(), getMap().replace(k0(), v3()));
    expectReplacement(entry(k0(), v3()));
  }

  @MapFeature.Require(SUPPORTS_PUT)

    Set<Entry<K, V>> entrySet = getMap().entrySet();
    Iterator<Entry<K, V>> entryItr = entrySet.iterator();
    assertEquals(e0(), entryItr.next());
    entryItr.remove();
    assertTrue(getMap().isEmpty());
    assertFalse(entrySet.contains(e0()));
  }

  public void testContainsEntryWithIncomparableKey() {
    try {

    Set<Entry<K, V>> entrySet = getMap().entrySet();
    Iterator<Entry<K, V>> entryItr = entrySet.iterator();
    assertEquals(e0(), entryItr.next());
    entryItr.remove();
    assertTrue(getMap().isEmpty());
    assertFalse(entrySet.contains(e0()));
  }

  public void testContainsEntryWithIncomparableKey() {
    try {

        "putIfAbsent(notPresent, value) should return null", getMap().putIfAbsent(k3(), v3()));
    expectAdded(e3());
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testPutIfAbsent_supportedPresent() {
    assertEquals(
        "putIfAbsent(present, value) should return existing value",
        v0(),
        getMap().putIfAbsent(k0(), v3()));
    expectUnchanged();
  }