If you want to test the integration you'll right you need that your local host will be acessable. The most easy way to do that is with ngrok. ngrok open your localhost with a temporary address. In my case the address will look like http://66a4cc4d.ngrok.io/nuntius-bot/WEBHOOK.

If you want to make sure that something happens you can log it to the logger entity:

Nuntius::getEntityManager()->get('logger')->insert(['foo' => 'bar']);

And then, to make sure something is going in the DB you can use the built in live entity view option:

php console.php nuntius:entity logger live_view

This will output the next result in the terminal: Setup