Very simple version of Isolates.

tests/isolate/nested_spawn_stream_test.dart

-// Copyright (c) 2012, 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.
-
-// Dart test program for testing that isolates can spawn other isolates.
-
-library NestedSpawnTest;
-import 'dart:isolate';
-import '../../pkg/unittest/lib/unittest.dart';
-
-void isolateA() {
-  IsolateSink replyTo;
-  bool isFirst = true;
-  stream.listen((msg) {
-    if (isFirst) {
-      isFirst = false;
-      replyTo = msg;
-      return;
-    }
-    expect(msg, "launch nested!");
-    IsolateSink sink = streamSpawnFunction(isolateB);
-    MessageBox box = new MessageBox();
-    sink.add(box.sink);
-    sink.add("alive?");
-    box.stream.single.then((msg) {
-      expect(msg, "and kicking");
-      replyTo.add(499);
-      replyTo.close();
-      stream.close();
-    });
-  });
-}
-
-void isolateB() {
-  IsolateSink replyTo;
-  bool isFirst = true;
-  stream.listen((msg) {
-    if (isFirst) {
-      isFirst = false;
-      replyTo = msg;
-      return;
-    }
-    expect(msg, "alive?");
-    replyTo.add("and kicking");
-    replyTo.close();
-    stream.close();
-  });
-}
-
-
-main() {
-  test("spawned isolates can spawn nested isolates", () {
-    MessageBox box = new MessageBox();
-    IsolateSink sink = streamSpawnFunction(isolateA);
-    sink.add(box.sink);
-    sink.add("launch nested!");
-    box.stream.single.then(expectAsync1((msg) {
-      expect(msg, 499);
-    }));
-  });
-}