More tests for async* functions

sdk/lib/_internal/js_runtime/lib/async_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/async_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/async_patch.dart b/sdk/lib/_internal/js_runtime/lib/async_patch.dart
index 4d91d7948c31ceb37b515b2a04f3641619b5f5cb..789ca256f45980a723db3145270aafbb29abf9ca 100644
--- a/sdk/lib/_internal/js_runtime/lib/async_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/async_patch.dart
@@ -255,10 +255,13 @@ _WrappedAsyncBody _wrapJsFunctionForAsync(dynamic /* js function */ function) {
 /// is done, schedules [asyncBody] again.
 ///
 /// If the async* function wants to do an await it calls this function with
-/// [object] not and [IterationMarker].
+/// [object] not an [IterationMarker].
 ///
 /// If [object] is not a [Future], it is wrapped in a `Future.value`.
 /// The [asyncBody] is called on completion of the future (see [asyncHelper].
+/// If the stream has been canceled in the meantime, the body is
+/// called with [async_error_codes.STREAM_WAS_CANCELED] once the future
+/// completes.

[Lasse Reichstein Nielsen, 2016/02/08 17:44:24]

That's not correct.
Canceled async* functions must only (attempt to) exit at a yield, not at an
await. That's documented above. It *must not* exit at an await.

[Lasse Reichstein Nielsen, 2016/02/08 20:54:44]

(or maybe I'm not understanding exactly what happens when this function is
called).

[floitsch, 2016/02/09 16:56:34]

My fault. I reverted these changes.

 void _asyncStarHelper(dynamic object,
     dynamic /* int | _WrappedAsyncBody */ bodyFunctionOrErrorCode,
     _AsyncStarStreamController controller) {
@@ -322,7 +325,17 @@ void _asyncStarHelper(dynamic object,
     }
   }
 
-  _awaitOnObject(object, bodyFunctionOrErrorCode);
+  // Executes the body-function, unless the subscription was canceled while
+  // waiting for the object.
+  void runBodyOrCancel(int errorCode, dynamic result) {
+    if (controller.isCanceled) {
+      bodyFunctionOrErrorCode(async_error_codes.STREAM_WAS_CANCELED, null);
+      return;
+    }
+    bodyFunctionOrErrorCode(errorCode, result);
+  }
+
+  _awaitOnObject(object, runBodyOrCancel);
 }
 
 Stream _streamOfController(_AsyncStarStreamController controller) {