title: python unit test: assertEqual on same objects throwing AssertionError
body: <p>I have a class as   </p>
  
  <pre><code>class PlaylistManager(models.Manager):
      def add_playlist(self, name):
          playlist = Playlist(name=name)
          playlist.save()
          return playlist
  
      def get_playlist_with_id(self, id):
          return super(PlaylistManager, self).get_query_set().filter(pk=id)
  
  class Playlist(models.Model):
      name = models.CharField(max_length=30)
      date_created = models.DateTimeField(auto_now_add=True)
      date_modified = models.DateTimeField(auto_now=True)
      deleted = models.BooleanField(default=False)
      objects = PlaylistManager() # is a customer manager
  
      def __repr__(self):
          return '&lt;Playlist name:%s, date_created:%s, date_modified:%s, deleted:%s&gt;' % \
                  (self.name, self.date_created, self.date_modified, self.deleted)
  
      class Meta:
          db_table = 'playlists'
  </code></pre>
  
  <p>and i <code>test</code> as  </p>
  
  <pre><code>def test_get_playlist(self):
      playlist = Utility.add_playlist()
      self.assertEqual(Playlist.objects.get_playlist_with_id(playlist.id), playlist)
  
  class Utility():
      @staticmethod
      def add_playlist(playlist_name=PLAYLIST):
          return Playlist.objects.add_playlist(playlist_name)
  </code></pre>
  
  <p>When I run the test, I see error as  </p>
  
  <pre><code>AssertionError: [&lt;Playlist name:playlist, date_created:2012-07-18 19:54:12.265909+00:00, date_modified:2012-07-18 19:54:12.265955+00:00, deleted:False&gt;] != &lt;Playlist name:playlist, date_created:2012-07-18 19:54:12.265909+00:00, date_modified:2012-07-18 19:54:12.265955+00:00, deleted:False&gt;
  </code></pre>
  
  <p>even when the two objects are same.</p>
  
  <p>Is there anything I am missing here?</p>