pkg/scheduled_test: handle null currentSchedule due to timeout

pkg/scheduled_test/test/scheduled_test/current_schedule_errors_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.
 
+import 'dart:async';
+
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/src/mock_clock.dart' as mock_clock;
 
 import '../metatest.dart';
 import '../utils.dart';
 
 void main(_, message) {
   initMetatest(message);
 
   setUpTimeout();
 
+  expectTests('a scheduled test with an out-of-band error should fail', () {
+    test('test 1', () {
+      sleep(5).then((_) => throw 'error');

[nweiz, 2014/04/10 00:58:15]

If you're going to use [sleep] like this, you need to call
`mock_clock.mock().run()` at the beginning of the block.

Also, there's no reason to sleep for 5 and 10 increments; just 1 and 2 will do.
Each increment corresponds to a full [pumpEventQueue] iteration.

+    });
+
+    test('test 2', () {
+      return sleep(10);
+    });
+  }, {'test 1': ERROR, 'test 2': PASS});
+
   expectTestsPass('currentSchedule.errors contains the error in the onComplete '
       'queue', () {
     var errors;
     test('test 1', () {
       currentSchedule.onComplete.schedule(() {
         errors = currentSchedule.errors;
       });
 
       throw 'error';
     });
@@ skipping 203 matching lines @@
         throw 'in-band';
       }));
     });
 
     test('test 2', () {
       expect(errors, everyElement(new isInstanceOf<ScheduleError>()));
       expect(errors.map((e) => e.error), equals(['in-band', 'out-of-band']));
     });
   }, passing: ['test 2']);
 }