'Test availability zone cache could be update.'

def test_update_host_availability_zone_cache(self):

    service = self._create_service_with_topic('compute', self.host)
    az_name = 'az1'
    cache_key = az._make_cache_key(self.host)
    agg_az1 = self._create_az('agg-az1', az_name)
    self._add_to_aggregate(service, agg_az1)
    az.update_host_availability_zone_cache(self.context, self.host)
    self.assertEqual('az1', az._get_cache().get(cache_key))
    az.update_host_availability_zone_cache(self.context, self.host, 'az2')
    self.assertEqual('az2', az._get_cache().get(cache_key))
