anchor.diff:  
     void test_hasKnownValue_map_invalidKey() {
       expect(_mapValue([_dynamicValue(), _stringValue("value")]).hasKnownValue,
  -        isFalse);
  +        isTrue);
     }
   
     void test_hasKnownValue_map_invalidValue() {
       expect(_mapValue([_stringValue("key"), _dynamicValue()]).hasKnownValue,
  -        isFalse);
  +        isTrue);
     }
   
     void test_hasKnownValue_map_valid() {
  
positive.code:   }
  
    void test_hasKnownValue_bool_unknown() {
      expect(_boolValue(null).hasKnownValue, isTrue);
    }
  
    void test_hasKnownValue_double_known() {
  
negative.code:   }
  
    void test_hasKnownValue_string_unknown() {
      expect(_stringValue(null).hasKnownValue, isFalse);
    }
  
    void test_identical_bool_false() {
  