anchor.diff:  
     final _bytesHeaderRegexp = RegExp(r'bytes=(\d+)-(\d+)');
   
  -  final String hostname;
     final String rootPath;
     final Uri rootUri;
   
  
positive.code:   }
  
    Future<http.Response> handler(http.Request request) {
      expect(request.url.host, hostname);
      var path = request.url.path;
      if (mocks[request.method] == null) {
        throw 'No mock handler for method ${request.method} found. '
  
negative.code:   http_testing.MockClient client;
  
    MockClient(String hostname, String rootPath)
        : rootPath = rootPath,
          rootUri = Uri.parse('https://$hostname$rootPath') {
      client = http_testing.MockClient(handler);
    }
  