'Ensure that modifications of related documents (through generic reference) don\'t influence on querying'

def test_generic_reference_list_item_modification(self):

    class Post(Document, ):
        title = StringField()
    class User(Document, ):
        username = StringField()
        bookmarks = ListField(GenericReferenceField())
    Post.drop_collection()
    User.drop_collection()
    post_1 = Post(title='Behind    the    Scenes    of    the    Pavement    Reunion')
    post_1.save()
    user = User(bookmarks=[post_1])
    user.save()
    post_1.title = 'Title    was    modified'
    user.username = 'New    username'
    user.save()
    user = User.objects(bookmarks__all=[post_1]).first()
    self.assertNotEqual(user, None)
    self.assertEqual(user.bookmarks[0], post_1)
