anchor.diff:      return pubListResult;
     }
   }
  +
  +class _MockProcessResult implements io.ProcessResult {
  +  @override
  +  final int pid;
  +
  +  @override
  +  final int exitCode;
  +
  +  @override
  +  final stdout;
  +
  +  @override
  +  final stderr;
  +
  +  _MockProcessResult(this.pid, this.exitCode, this.stdout, this.stderr);
  +}
  
positive.code:   io.ProcessResult pubListResult;
  
    void setPubListError() {
      pubListResult = new io.ProcessResult(0, 1, '', 'ERROR');
    }
  
    void setPubListResult({Map<String, String> packages: const {},
        List<String> input_files: const []}) {
      pubListResult = new io.ProcessResult(0, 0,
          JSON.encode({'packages': packages, 'input_files': input_files}), '');
    }
  
  
negative.code: 
    test_computePackageMap_noPreviousInfo_pubListError() {
      String pubspecLock = posix.join(projectFolder.path, 'pubspec.lock');
      setPubListError();
      OptimizingPubPackageMapInfo info =
          provider.computePackageMap(projectFolder);
  