async def METHOD_NAME(self):
    mock_sub = mock.Mock(spec=Subscription)
    future = asyncio.Future()
    future.set_result(mock_sub)
    self.mock_nats_client.subscribe.return_value = future
    topic = 'bar'
    await self.sub_trans.subscribe(topic, self.callback)
    self.mock_nats_client.subscribe.assert_called_once_with(
        'frugal.bar',
        queue=self.queue,
        cb=mock.ANY,
    )
    self.assertEqual(self.sub_trans._subscription, mock_sub)