anchor.diff:  
   @reflectiveTest
   class ErrorCodeValuesTest extends ParserTestCase {
  -  List<String> _rootComponents;
  -
  -  List<String> get rootComponents {
  -    if (_rootComponents == null) {
  -      List<String> components = path.split(package_root.packageRoot);
  -      components.add('analyzer');
  -      _rootComponents = components;
  -    }
  -    return _rootComponents;
  -  }
  -
     bool bad() {
       return false;
     }
  
positive.code: import 'dart:io';
  
  import 'package:analyzer/dart/ast/ast.dart';
  import 'package:front_end/src/testing/package_root.dart' as package_root;
  import 'package:path/path.dart' as path;
  import 'package:test/test.dart';
  import 'package:test_reflective_loader/test_reflective_loader.dart';
  
  import '../generated/parser_test.dart';
  
  main() {
    defineReflectiveSuite(() {
      defineReflectiveTests(ErrorCodeValuesTest);
    });
  
negative.code:   }
  
    CompilationUnit parseFile(List<String> relativeComponents) {
      List<String> pathComponents = _analyzerRootComponents.toList()
        ..addAll(relativeComponents);
      String filePath = path.normalize(path.joinAll(pathComponents));
      return parseCompilationUnit(new File(filePath).readAsStringSync());
  