Refactor outstdanding callbacks in invoker.dart.

test/backend/invoker_test.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:async';
 
 import 'package:fake_async/fake_async.dart';
 import 'package:test/src/backend/invoker.dart';
 import 'package:test/src/backend/metadata.dart';
 import 'package:test/src/backend/state.dart';
@@ skipping 624 matching lines @@
         expectErrors(liveTest, [(error) {
           expect(lastState.status, equals(Status.complete));
           expect(error, new isInstanceOf<TimeoutException>());
         }]);
 
         liveTest.run();
         async.elapse(new Duration(seconds: 15));
       });
     });
   });
+
+  group("waitForOutstandingCallbacks:", () {
+    test("waits for the wrapped function to complete", () async {
+      var functionCompleted = false;
+      await Invoker.current.waitForOutstandingCallbacks(() async {
+        await pumpEventQueue();
+        functionCompleted = true;
+      });
+
+      expect(functionCompleted, isTrue);
+    });
+
+    test("waits for registered callbacks in the wrapped function to run",
+        () async {
+      var callbackRun = false;
+      await Invoker.current.waitForOutstandingCallbacks(() {
+        pumpEventQueue().then(expectAsync((_) {
+          callbackRun = true;
+        }));
+      });
+
+      expect(callbackRun, isTrue);
+    });
+
+    test("doesn't automatically block the enclosing context", () async {
+      var innerFunctionCompleted = false;
+      await Invoker.current.waitForOutstandingCallbacks(() {
+        Invoker.current.waitForOutstandingCallbacks(() async {
+          await pumpEventQueue();
+          innerFunctionCompleted = true;
+        });
+      });
+
+      expect(innerFunctionCompleted, isFalse);
+    });
+  });
 }
 
 LocalTest _localTest(body(), {tearDown(), Metadata metadata}) {
   if (metadata == null) metadata = new Metadata();
   return new LocalTest("test", metadata, body, tearDown: tearDown);
 }