If computation of Stream.periodic throws, forward the error to the stream.

tests/lib/async/stream_periodic6_test.dart

 // Copyright (c) 2013, 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 merging streams.
 library dart.test.stream_from_iterable;
 
 import "dart:async";
 import 'package:unittest/unittest.dart';
 
 main() {
   test("stream-periodic1", () {
-    Stream stream = new Stream.periodic(const Duration(milliseconds: 1));
-    int receivedCount = 0;
+    Stream stream = new Stream.periodic(const Duration(milliseconds: 1),
+                                        (i) {
+                                          if (i == 3) throw 42;
+                                          return i;
+                                        });
+    int expected = 0;
     var subscription;
     subscription = stream.listen(expectAsync((data) {
-      expect(data, isNull);
-      receivedCount++;
-      if (receivedCount == 5) subscription.cancel();
-    }, count: 5));
+      expect(data, expected++);
+      if (expected == 5) subscription.cancel();
+    }, count: 4),
+    onError: expectAsync((e, s) {
+      expect(e, 42);

[floitsch, 2015/10/31 00:10:08]

maybe also check, that expected == 3.
Not necessary, though.
However, you should check, that this line is actually executed.

[Lasse Reichstein Nielsen, 2015/10/31 11:09:10]

I think the expectAsync ensures that the function is called once.

[floitsch, 2015/10/31 19:51:30]

Right. Missed that one...

+      expected++;
+    }));
   });
 }