anchor.diff:  
     /// 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) {
  +  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)) {
  +      if (!data.containsKey(name) ||
  +          _blacklistedOptions.contains(name) ||
  +          (usingNamedConfiguration &&
  +              _namedConfigurationOptions.contains(name))) {
           continue;
         }
   
  
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:     '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.
  