def METHOD_NAME(self):
    pk = 1
    event = self.client.get(event_api._get_detail_url(pk))
    event_data = event.json()
    del event_data["cover"]
    # Make sure that we're not adding a tag which is there already.
    # The simplest way to do this is to ensure that the event has no tags.
    self.assertEqual(len(event_data.pop("tags")), 0)
    tag = Tag.objects.first()
    event_data["tags"] = [tag.tag]
    res = self.client.put(event_api._get_detail_url(pk), event_data)
    self.assertEqual(res.status_code, status.HTTP_200_OK)
    self.assertTrue(tag.tag in res.json().pop("tags"))