Fix issue with async callbacks that get called synchronously while running test case function causi…

pkg/unittest/lib/src/test_case.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.
 
 part of unittest;
 
 /**
  * testcase.dart: this file is sourced by unittest.dart. It defines [TestCase]
  * and assumes unittest defines the type [TestFunction].
  */
@@ skipping 60 matching lines @@
   bool get isComplete => !enabled || result != null;
 
   void _prepTest() {
     _config.onTestStart(this);
     startTime = new DateTime.now();
     runningTime = null;
   }
 
   Future _runTest() {
     _prepTest();
+    // Increment/decrement callbackFunctionsOutstanding to prevent
+    // synchronous 'async' callbacks from causing the  test to be
+    // marked as complete before the body is completely executed.
+    ++callbackFunctionsOutstanding;
     var f = test();
+    --callbackFunctionsOutstanding;
     if (f is Future) {
       f.then((_) => _finishTest())
        .catchError((e) => fail("${e.error}"));
       return f;
     } else {
       _finishTest();
       return null;
     }
   }
 
@@ skipping 105 matching lines @@
       // TODO(gram): Should we combine the stack with the old one?
       _complete(ERROR, newMessage, stack);
     } else {
       _complete(FAIL, messageText, stack);
     }
   }
 
   void error(String messageText, [String stack = '']) {
     _complete(ERROR, messageText, stack);
   }
+
+  void markCallbackComplete() {
+    if (--callbackFunctionsOutstanding == 0 && !isComplete) {
+      pass();
+    }
+  }
 }