Very simple version of Isolates.

tests/standalone/io/pipe_server_test.dart

 // Copyright (c) 2013, 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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 library ServerTest;
 
 import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
 import "dart:async";
 import "dart:io";
 import "dart:isolate";
 part "testing_server.dart";
 
 
 String getDataFilename(String path) =>
     new File(path).existsSync() ? path : '../$path';
 
 
 bool compareFileContent(String fileName1, String fileName2) {
   var contents1 = new File(fileName1).readAsStringSync();
   var contents2 = new File(fileName2).readAsStringSync();
   return contents1 == contents2;
 }
 
 
 // This test does:
 //  1. Opens a socket to the testing server.
 //  2. Pipes the content of a file to that sockets input stream.
 //  3. Creates a temp file.
 //  4. Pipes the socket output stream to the temp file.
 //  5. Expects the original file and the temp file to be equal.
 class PipeServerGame {
 
   int count = 0;
 
   PipeServerGame.start()
-      : _receivePort = new ReceivePort(),
-        _sendPort = null,
-        _messages = 0 {
-    _sendPort = spawnFunction(startPipeServer);
+      : _messages = 0 {
     initialize();
   }
 
   void runTest() {
 
     void connectHandler() {
       String srcFileName =
           getDataFilename("tests/standalone/io/readline_test1.dat");
       Stream fileInput = new File(srcFileName).openRead();
       fileInput.pipe(_socket).then((_) {
@@ skipping 21 matching lines @@
     }
 
     // Connect to the server.
     Socket.connect(TestingServer.HOST, _port).then((s) {
       _socket = s;
       connectHandler();
     });
   }
 
   void initialize() {
-    _receivePort.receive((var message, SendPort replyTo) {
-      _port = message;
+    var receivePort = new ReceivePort();
+    var remote = Isolate.spawn(startPipeServer, receivePort.sendPort);
+    receivePort.first.then((msg) {
+      this._port = msg[0];
+      this._closeSendPort = msg[1];
       runTest();
     });
-    _sendPort.send(TestingServer.INIT, _receivePort.toSendPort());
   }
 
   void shutdown() {
-    _sendPort.send(TestingServer.SHUTDOWN, _receivePort.toSendPort());
-    _receivePort.close();
+    _closeSendPort.send(null);
+    asyncEnd();
   }
 
   int _port;
-  ReceivePort _receivePort;
-  SendPort _sendPort;
+  SendPort _closeSendPort;
   Socket _socket;
   int _messages;
 }
 
 
-void startPipeServer() {
+void startPipeServer(SendPort replyPort) {
   var server = new PipeServer();
-  port.receive(server.dispatch);
+  server.init().then((port) {
+    replyPort.send([port, server.closeSendPort]);
+  });
 }
 
 
 // The testing server will simply pipe each connecting sockets input
 // stream to its output stream.
 class PipeServer extends TestingServer {
   void onConnection(Socket connection) {
     connection.pipe(connection);
   }
 }
 
 
 main() {
+  asyncStart();
   PipeServerGame echoServerGame = new PipeServerGame.start();
 }