anchor.diff:      var pReference = findNode.simple('p +=');
       expect(pReference.staticElement, same(pElement));
       expect(pReference.staticType, isNull);
  +  }
  +
  +  test_assignment_to_unresolved_name() async {
  +    addTestFile('''
  +f(int y) {
  +  x = y;
  +}
  +''');
  +    await resolveTestFile();
  +    expect(result.errors, isNotEmpty);
  +    var yElement = findElement.parameter('y');
  +    assertElement(findNode.simple('y;'), yElement);
     }
   
     test_assignmentExpression_compound_indexExpression() async {
  
positive.code:     assertElement(findNode.simple('y;'), yElement);
    }
  
    test_compound_assignment_of_unresolved_name() async {
      addTestFile('''
  f(int y) {
    x += y;
  
negative.code:     }
    }
  
    test_null_aware_assignment_to_postfix_increment() async {
      addTestFile('''
  f(int x, int y) {
    x++ ??= y;
  