Also generate error when autogenerating stack traces (fix #25)

test/logging_test.dart

 // Copyright (c) 2012, 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.
 
 library logging_test;
 
 import 'dart:async';
 
 import 'package:logging/logging.dart';
 import 'package:test/test.dart';
@@ skipping 551 matching lines @@
       }
       var records = new List<LogRecord>();
       recordStackTraceAtLevel = Level.WARNING;
       root.onRecord.listen(records.add);
       root.severe('hello');
       root.warning('hello', 'a', trace);
       expect(records, hasLength(2));
       expect(records[0].stackTrace, isNot(equals(trace)));
       expect(records[1].stackTrace, trace);
     });
+
+    test('error also generated when generating a trace', () {
+      var records = new List<LogRecord>();
+      recordStackTraceAtLevel = Level.WARNING;
+      root.onRecord.listen(records.add);
+      root.severe('hello');
+      root.warning('hello');
+      root.info('hello');
+      expect(records, hasLength(3));
+      expect(records[0].error, isNotNull);
+      expect(records[1].error, isNotNull);
+      expect(records[2].error, isNull);
+    });
   });
 }