anchor.diff:      diagnostics = [];
     }
   
  -  factory TestOutputImpl.fromCase (TestCase testCase, int exitCode, bool timedOut,
  -                                   List<String> stdout, List<String> stderr, Duration time) {
  +  factory TestOutputImpl.fromCase (TestCase testCase,
  +                                   int exitCode,
  +                                   bool timedOut,
  +                                   List<String> stdout,
  +                                   List<String> stderr,
  +                                   Duration time) {
       if (testCase is BrowserTestCase) {
         return new BrowserTestOutputImpl(testCase, exitCode, timedOut,
           stdout, stderr, time);
  
positive.code:       print("  Command: $command");
        print("  Error: $e");
      };
      startTime = new Date.now();
      InputStream stdoutStream = process.stdout;
      InputStream stderrStream = process.stderr;
      StringInputStream stdoutStringStream = new StringInputStream(stdoutStream);
  
negative.code:     stdout = new List<String>();
      stderr = new List<String>();
      currentStep = 0;
      startTime = new Date.now();
      runCommand(testCase.commands[currentStep++], stepExitHandler);
    }
  
  