anchor.diff:  Future<String> _read(HttpServer server) => http.read(_urlFor(server));
   
   /// Returns the URL for the root of [server].
  -String _urlFor(HttpServer server) =>
  -    'http://${server.address.host}:${server.port}/';
  +Uri _urlFor(HttpServer server) =>
  +    Uri.http('${server.address.host}:${server.port}', '/');
  
positive.code:       });
  
        if (await supportsIPv4) {
          expect(http.read('http://127.0.0.1:${server.port}/'),
              completion(equals('got request')));
        }
  
        if (await supportsIPv6) {
          expect(http.read('http://[::1]:${server.port}/'),
              completion(equals('got request')));
        }
      });
  
negative.code:       });
  
        if (await supportsIPv4) {
          expect(http.read(Uri.http('127.0.0.1:${server.port}', '/')),
              completion(equals('got request')));
        }
  
        if (await supportsIPv6) {
          expect(http.read(Uri.http('[::1]:${server.port}', '/')),
              throwsA(isA<SocketException>()));
        }
      });
  