anchor.diff:      'write_results',
     ].toSet();
   
  +  /// The set of objects which the named configuration should imply.
  +  static final _namedConfigurationOptions = [
  +    'system',
  +    'arch',
  +    'mode',
  +    'compiler',
  +    'runtime',
  +  ].toSet();
  +
     /// Parses a list of strings as test options.
     ///
     /// Returns a list of configurations in which to run the tests.
  
positive.code:                 packageRoot: data["package_root"] as String,
                  suiteDirectory: data["suite_dir"] as String,
                  outputDirectory: data["output_directory"] as String,
                  reproducingArguments: _reproducingCommand(data),
                  fastTestsOnly: data["fast_tests"] as bool,
                  printPassingStdout: data["print_passing_stdout"] as bool);
  
  
negative.code: 
    /// Given a set of parsed option values, returns the list of command line
    /// arguments that would reproduce that configuration.
    List<String> _reproducingCommand(
        Map<String, dynamic> data, bool usingNamedConfiguration) {
      var arguments = <String>[];
  
      for (var option in _options) {
        var name = option.name;
        if (!data.containsKey(name) ||
            _blacklistedOptions.contains(name) ||
            (usingNamedConfiguration &&
                _namedConfigurationOptions.contains(name))) {
          continue;
        }
  
  