Very simple version of Isolates.

runtime/tests/vm/dart/isolate_unhandled_exception_test2.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.
-
-library isolate_unhandled_exception_test2;
-
-import 'dart:isolate';
-
-// Tests that an isolate's keeps message handling working after
-// throwing an unhandled exception, if there is a top level callback
-// method that returns whether to continue handling messages or not.
-// This test verifies that a default-named callback function is called
-// when no callback is specified in Isolate.spawnFunction.
-
-// Note: this test will hang if an uncaught exception isn't handled,
-// either by an error in the callback or it returning false.
-
-void entry() {
-  port.receive((message, replyTo) {
-    if (message == 'throw exception') {
-      replyTo.call('throwing exception');
-      throw new UnsupportedError('ignore this exception');
-    }
-    replyTo.call('hello');
-    port.close();
-  });
-}
-
-bool _unhandledExceptionCallback(IsolateUnhandledException e) {
-  return e.source.message == 'ignore this exception';
-}
-
-void main() {
-  var isolate_port = spawnFunction(entry);
-
-  // Send a message that will cause an ignorable exception to be thrown.
-  Future f = isolate_port.call('throw exception');
-  f.onComplete((future) {
-    // Exception wasn't ignored as it was supposed to be.
-    Expect.equals(null, future.exception);
-  });
-
-  // Verify that isolate can still handle messages.
-  isolate_port.call('hi').onComplete((future) {
-    Expect.equals(null, future.exception);
-    Expect.equals('hello', future.value);
-  });
-
-}