add a comment to the generated lock file

utils/tests/pub/lock_file_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 lock_file_test;
 
 import '../../../pkg/unittest/lib/unittest.dart';
 import '../../../pkg/yaml/lib/yaml.dart';
 import '../../pub/lock_file.dart';
 import '../../pub/package.dart';
@@ skipping 144 matching lines @@
       });
     });
 
     group('serialize()', () {
       test('dumps the lockfile to YAML', () {
         var lockfile = new LockFile.empty();
         lockfile.packages['foo'] = new PackageId(
             'foo', mockSource, new Version.parse('1.2.3'), 'foo desc');
         lockfile.packages['bar'] = new PackageId(
             'foo', mockSource, new Version.parse('3.2.1'), 'bar desc');
-
-        expect(loadYaml(lockfile.serialize()), equals({
+        
+        expect(loadYaml(lockfile.serialize().replaceAll(LockFile.comment, '')), equals({

[Bob Nystrom, 2013/01/31 22:17:44]

This shouldn't be needed. If it is, there's a bug in YAML! :)

[keertip, 2013/01/31 22:23:39]

If the comment is not removed, loadYaml fails and returns null

On 2013/01/31 22:17:44, Bob Nystrom wrote:

[keertip, 2013/01/31 22:31:40]

Guess that was because the comment should be on a separate line! Will make the
changes.
 
On 2013/01/31 22:23:39, keertip wrote:

[Bob Nystrom, 2013/01/31 22:33:48]

That was my hunch too. :)

           'packages': {
             'foo': {
               'version': '1.2.3',
               'source': 'mock',
               'description': 'foo desc'
             },
             'bar': {
               'version': '3.2.1',
               'source': 'mock',
               'description': 'bar desc'
             }
           }
         }));
       });
     });
   });
 }