Add Isolate ping functionality.

tests/isolate/ping_test.dart

+// Copyright (c) 2014, 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:isolate";
+import "dart:async";
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+
+isomain1(replyPort) {
+  RawReceivePort port = new RawReceivePort();
+  port.handler = (v) {
+    replyPort.send(v);
+    if (v == 0) port.close();
+  };
+  replyPort.send(port.sendPort);
+}
+
+void main(){
+  asyncStart();
+  var completer = new Completer();  // Completed by first reply from isolate.
+  RawReceivePort reply = new RawReceivePort(completer.complete);
+  Isolate.spawn(isomain1, reply.sendPort).then((Isolate isolate) {
+    List result = [];
+    completer.future.then((echoPort) {
+      reply.handler = (v) {
+        result.add(v);
+        if (v == 0) {
+          Expect.listEquals(["alive", "control", "event"],
+                            result.where((x) => x is String).toList());
+          Expect.listEquals([4, 3, 2, 1, 0],
+                            result.where((x) => x is int).toList());
+          Expect.isTrue(result.indexOf("alive") < result.indexOf(3));
+          Expect.isTrue(result.indexOf("control") < result.indexOf(2));
+          int eventIndex = result.indexOf("event");
+          Expect.isTrue(eventIndex > result.indexOf(2));
+          Expect.isTrue(eventIndex < result.indexOf(1));
+          reply.close();
+          asyncEnd();
+        }
+      };
+      echoPort.send(4);
+      SendPort createPingPort(message) {
+        var pingPort = new RawReceivePort();
+        pingPort.handler = (_) {
+          result.add(message);
+          pingPort.close();
+        };
+        return pingPort.sendPort;
+      }
+      isolate.ping(createPingPort("alive"), Isolate.PING_ALIVE);
+      echoPort.send(3);
+      isolate.ping(createPingPort("control"), Isolate.PING_CONTROL);
+      echoPort.send(2);
+      isolate.ping(createPingPort("event"), Isolate.PING_EVENT);
+      echoPort.send(1);
+      echoPort.send(0);
+    });
+  });
+}