anchor.diff:  }
   ''');
   
  -    assertConstraint([decoratedTypeAnnotation('int/*3*/').node.nullable],
  -        decoratedTypeAnnotation('int/*1*/').node.nullable);
  +    assertConnection(decoratedTypeAnnotation('int/*3*/').node,
  +        decoratedTypeAnnotation('int/*1*/').node);
       assertNullCheck(checkExpression('c/*check*/'),
           decoratedTypeAnnotation('C<int/*3*/>/*4*/').node,
           contextNode: decoratedTypeAnnotation('C<int/*1*/>/*2*/').node);
  
positive.code: }
  ''');
      var optional_i = possiblyOptionalParameter('int i');
      assertConstraint([], optional_i.nullable);
    }
  
    test_functionInvocation_parameter_named_missing_required() async {
  
negative.code: void f({int i = null}) {}
  ''');
  
      assertConnection(
          NullabilityNode.always, decoratedTypeAnnotation('int').node);
    }
  
    test_functionDeclaration_parameter_named_no_default_assume_nullable() async {
  