Laravel 5.3 - Avoid sending slack notification in phpunit test

So I've got a test set up that visits the sign up page and submits the form. Then the test verifies the account by token.

Once the account has been verified, a notification is sent through a SlackMessage.

What I was wondering is how can I intercept this, and stop the slack message from actually sending - only when running a test, but get some kind of confirmation that the notification did in fact get called.

via Chebli Mohamed