anchor.diff:    List<String> stackTrace;
   
     TestResult(this.testName, this.expected, this.actual);
  +
  +  String get traceLine {
  +    for (int i = 0; i < stackTrace.length; i++) {
  +      String traceLine = stackTrace[i];
  +      if (traceLine.startsWith(framePattern) &&
  +          traceLine.contains('(package:')) {
  +        return traceLine;
  +      }
  +    }
  +    return null;
  +  }
   }
  
positive.code:       print('  $message');
      }
    }
  }
  
  /// A representation of the result of a single test.
  class TestResult {
    String testName;
    String expected;
    String actual;
  
negative.code:   final int actualPrefixLength = 'Actual: '.length;
    TestResult currentResult;
    Map<String, List<TestResult>> testsByExpectedAndActual =
        <String, List<TestResult>>{};
    Map<String, List<TestResult>> testsByStackTrace =
        <String, List<TestResult>>{};
    while (index < output.length) {
      String currentLine = output[index];
  