Stream isolates.

tests/corelib/stream_controller_test.dart

 // Copyright (c) 2011, 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.
 
 // Test the basic ControllerStream.
 import 'dart:async';
 
 class Event {
   void replay(StreamSink sink);
 }
@@ skipping 237 matching lines @@
   Expect.listEquals(expectedEvents.events, actualEvents.events);
   expectedEvents..write(44)..write(45)..close();
   sub.onDone(() {
     // This depends on the captured events in actualEvents being filled
     // before sub.onDone is called. That's slightly hacky. We need a
     // way to write async tests (this file is really depending on
     // synchronous event propagation).
     Expect.listEquals(expectedEvents.events, actualEvents.events);
   });
   signal.complete();
+
+  // Test subscription changes while firing.
+  c = new StreamController();
+  var sink = c.sink;
+  var stream = c.stream;
+  var counter = 0;
+  var subscription = stream.subscribe();
+  subscription.onData((data) {
+    counter += data;
+    subscription.unsubscribe();
+    stream.subscribe(onData: (data) {
+      counter += 10 * data;
+    });
+    var subscription2 = stream.subscribe();
+    subscription2.onData((data) {
+      counter += 100 * data;
+      if (data == 4) subscription2.unsubscribe();
+    });
+  });
+  sink.write(1); // seen by stream 1
+  sink.write(2); // seen by stream 10 and 100
+  sink.write(3); // -"-
+  sink.write(4); // -"-
+  sink.write(5); // seen by stream 10
+  Expect.equals(1 + 20 + 200 + 30 + 300 + 40 + 400 + 50, counter);
 }