Modify address used in tests to be IPv agnostic and not use 127.0.0.1, to support IPv6 only environ…

test/http_basic_test.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "dart:async";
+import "dart:io";
 import "dart:isolate";
-import "dart:io";
+
 import "package:sync_http/sync_http.dart";
 import "package:test/test.dart";
 
 typedef void ServerCallback(int port);
 
 class TestServerMain {
   TestServerMain() : _statusPort = new ReceivePort();
 
   ReceivePort _statusPort; // Port for receiving messages from the server.
   SendPort _serverPort; // Port for sending messages to the server.
@@ skipping 148 matching lines @@
     _requestHandlers["/0123456789"] = _zeroToTenHandler;
     _requestHandlers["/reasonformoving"] = _reasonForMovingHandler;
     _requestHandlers["/host"] = _hostHandler;
     _requestHandlers["/huge"] = _hugeHandler;
     _dispatchPort = new ReceivePort();
     _dispatchPort.listen(dispatch);
   }
 
   SendPort get dispatchSendPort => _dispatchPort.sendPort;
 
-  void dispatch(var message) {
+  dispatch(var message) async {
     TestServerCommand command = message[0];
     SendPort replyTo = message[1];
     if (command.isStart) {
       try {
-        HttpServer.bind("127.0.0.1", 0).then((server) {
+        var addr = (await InternetAddress.lookup("localhost"))[0];
+        HttpServer.bind(addr, 0).then((server) {
           _server = server;
           _server.listen(_requestReceivedHandler);
           replyTo.send(new TestServerStatus.started(_server.port));
         });
       } catch (e) {
         replyTo.send(new TestServerStatus.error());
       }
     } else if (command.isStop) {
       _server.close();
       _dispatchPort.close();
@@ skipping 24 matching lines @@
   });
   testServerMain.start();
   return completer.future;
 }
 
 Future testGET() async {
   Completer completer = new Completer();
   TestServerMain testServerMain = new TestServerMain();
   testServerMain.setServerStartedHandler((int port) {
     var request =
-        SyncHttpClient.getUrl(new Uri.http("127.0.0.1:$port", "/0123456789"));
+        SyncHttpClient.getUrl(new Uri.http("localhost:$port", "/0123456789"));
     var response = request.close();
     expect(HttpStatus.OK, equals(response.statusCode));
     expect(11, equals(response.contentLength));
     expect("01234567890", equals(response.body));
     testServerMain.close();
     completer.complete();
   });
   testServerMain.start();
   return completer.future;
 }
 
 Future testPOST() async {
   Completer completer = new Completer();
   String data = "ABCDEFGHIJKLMONPQRSTUVWXYZ";
   final int kMessageCount = 10;
 
   TestServerMain testServerMain = new TestServerMain();
 
   void runTest(int port) {
     int count = 0;
     void sendRequest() {
       var request =
-          SyncHttpClient.postUrl(new Uri.http("127.0.0.1:$port", "/echo"));
+          SyncHttpClient.postUrl(new Uri.http("localhost:$port", "/echo"));
       request.write(data);
       var response = request.close();
       expect(HttpStatus.OK, equals(response.statusCode));
       expect(data, equals(response.body));
       count++;
       if (count < kMessageCount) {
         sendRequest();
       } else {
         testServerMain.close();
         completer.complete();
       }
     }
 
     sendRequest();
   }
 
   testServerMain.setServerStartedHandler(runTest);
   testServerMain.start();
   return completer.future;
 }
 
 Future test404() async {
   Completer completer = new Completer();
   TestServerMain testServerMain = new TestServerMain();
   testServerMain.setServerStartedHandler((int port) {
     var request = SyncHttpClient
-        .getUrl(new Uri.http("127.0.0.1:$port", "/thisisnotfound"));
+        .getUrl(new Uri.http("localhost:$port", "/thisisnotfound"));
     var response = request.close();
     expect(HttpStatus.NOT_FOUND, equals(response.statusCode));
     expect("Page not found", equals(response.body));
     testServerMain.close();
     completer.complete();
   });
   testServerMain.start();
   return completer.future;
 }
 
 Future testReasonPhrase() async {
   Completer completer = new Completer();
   TestServerMain testServerMain = new TestServerMain();
   testServerMain.setServerStartedHandler((int port) {
     var request = SyncHttpClient
-        .getUrl(new Uri.http("127.0.0.1:$port", "/reasonformoving"));
+        .getUrl(new Uri.http("localhost:$port", "/reasonformoving"));
     var response = request.close();
     expect(HttpStatus.MOVED_PERMANENTLY, equals(response.statusCode));
     expect(
         "Don't come looking here any more\r\n", equals(response.reasonPhrase));
     testServerMain.close();
     completer.complete();
   });
   testServerMain.start();
   return completer.future;
 }
 
 Future testHuge() async {
   Completer completer = new Completer();
   TestServerMain testServerMain = new TestServerMain();
   testServerMain.setServerStartedHandler((int port) {
     var request =
-        SyncHttpClient.getUrl(new Uri.http("127.0.0.1:$port", "/huge"));
+        SyncHttpClient.getUrl(new Uri.http("localhost:$port", "/huge"));
     var response = request.close();
     String expected =
         new List<int>.generate((1 << 20), (i) => (i + 1) % 256).toString();
     expect(HttpStatus.OK, equals(response.statusCode));
     expect(expected.length, equals(response.contentLength));
     expect(expected.toString(), equals(response.body));
     testServerMain.close();
     completer.complete();
   });
   testServerMain.start();
@@ skipping 13 matching lines @@
   test("Sync HTTP 404 test", () async {
     await test404();
   });
   test("Sync HTTP moved test", () async {
     await testReasonPhrase();
   });
   test("Sync HTTP huge test", () async {
     await testHuge();
   });
 }