async def METHOD_NAME(self):
    mock_sub = mock.Mock(spec=Subscription)
    self.sub_trans._is_subscribed = True
    self.sub_trans._subscription = mock_sub
    future = asyncio.Future()
    future.set_result(None)
    mock_sub.unsubscribe.return_value = future
    await self.sub_trans.unsubscribe()
    self.assertIsNone(self.sub_trans._subscription)
    self.assertFalse(self.sub_trans._is_subscribed)
    mock_sub.unsubscribe.assert_called_once()