anchor.diff:  /// lists all tests included for that particular configuration.
   Future<Iterable<String>> testLister(Configuration configuration) async {
     var args = configuration.toArgs()..add("--list");
  -  var testPyPath = path.absolute(PathHelper.testPyPath());
  -  var result = await Process.run(testPyPath, args);
  -  if (result.exitCode != 0) {
  -    throw "Failed to list tests: "
  -        "'${PathHelper.testPyPath()} ${args.join(' ')}'. "
  -        "Process exited with ${result.exitCode}";
  -  }
  -  return (result.stdout as String)
  -      .split('\n')
  -      .skip(1)
  +  return (await callTestPy(args))
         .map((line) => line.trim())
         .where((name) => name.isNotEmpty);
   }
  
positive.code: /// Calls test.py with arguments gathered from a specific [configuration] and
  /// lists all status files included for that particular configuration.
  Future<Iterable<String>> statusFileLister(Configuration configuration) async {
    var args = configuration.toArgs()..add("--list-status-files");
    var testPyPath = path.absolute(PathHelper.testPyPath());
    var result = await Process.run(testPyPath, args);
    if (result.exitCode != 0) {
      throw "Failed to list tests: "
          "'${PathHelper.testPyPath()} ${args.join(' ')}'. "
          "Process exited with ${result.exitCode}";
    }
    return (result.stdout as String)
        .split('\n')
        .skip(1)
        .where((name) => name.isNotEmpty);
  }
  
  /// Calls test.py with arguments gathered from a specific [configuration] and
  /// returns a map from test-suite to a list of status-files.
  Future<Map<String, Iterable<String>>> statusFileListerMap(
      Configuration configuration) async {
    Map<String, List<String>> returnMap = {};
    var suitesWithStatusFiles = await statusFileLister(configuration);
    String currentSuite = "";
    for (var line in suitesWithStatusFiles) {
      bool isSuiteLine = !line.startsWith("\t");
      if (isSuiteLine) {
        currentSuite = line;
  
negative.code:   }
    return returnMap;
  }
  
  /// Get tests for a suite.
  Future<Iterable<String>> testsForSuite(String suite) async {
    Iterable<String> tests = await callTestPy(["--list", suite]);
    return tests
        .skip(3)
        .takeWhile((testName) => testName.isNotEmpty)
        .map((testInfo) {
      return testInfo.substring(0, testInfo.indexOf(" ")).trim();
    });
  }
  