'Ensure that a document may be saved with a custom _id.'

def test_save_custom_id(self):

    person = self.Person(name='Test    User', age=30, id='497ce96f395f2f052a494fd4')
    person.save()
    collection = self.db[self.Person._get_collection_name()]
    person_obj = collection.find_one({'name': 'Test    User'})
    self.assertEqual(str(person_obj['_id']), '497ce96f395f2f052a494fd4')
