anchor.diff:    /// appropriate exit code.
     Future<int> run() async {
       var frontEndUris = await findFrontEndUris();
  -    var packagesFileUri = frontEndRootUri.resolve('../../.packages');
  +    var packagesFileUri = frontEndLibUri.resolve('../../../.packages');
       var graph = await graphForProgram(
           frontEndUris,
           new CompilerOptions()
  
positive.code: }
  
  class _SubpackageRelationshipsTest {
    /// File uri of the root of the front_end package.
    final frontEndRootUri = Platform.script.resolve('..');
  
    /// Indicates whether any problems have been reported yet.
    bool problemsReported = false;
  
negative.code: 
    /// Finds all files in the front_end's "lib" directory and returns their Uris
    /// (as "package:" URIs).
    List<Uri> findFrontEndUris() {
      var frontEndUris = <Uri>[];
      var frontEndLibPath = pathos.fromUri(frontEndLibUri);
      for (var entity in new Directory(frontEndLibPath)
          .listSync(recursive: true, followLinks: false)) {
        if (entity is File && entity.path.endsWith('.dart')) {
          var posixRelativePath = pathos.url.joinAll(
              pathos.split(pathos.relative(entity.path, from: frontEndLibPath)));
          frontEndUris.add(Uri.parse('package:front_end/$posixRelativePath'));
        }
      }
      return frontEndUris;
  