anchor.diff:                  packageRoot: data["package_root"] as String,
                   suiteDirectory: data["suite_dir"] as String,
                   outputDirectory: data["output_directory"] as String,
  -                reproducingArguments: _reproducingCommand(data),
  +                reproducingArguments:
  +                    _reproducingCommand(data, namedConfiguration != null),
                   fastTestsOnly: data["fast_tests"] as bool,
                   printPassingStdout: data["print_passing_stdout"] as bool);
   
  
positive.code:     'write_results',
    ].toSet();
  
    /// Parses a list of strings as test options.
    ///
    /// Returns a list of configurations in which to run the tests.
  
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;
        }
  
  