Mentionable Usernames with TDD

For the next version of the Laracasts forum, we offer a small feature that provides @username autocompletion when writing a new reply. To populate this list of usernames, we reference the conversation owner, every person who has left a reply, and all usernames who have been mentioned within those replies. Let me show you how to construct this very logic from scratch, using TDD. This lesson will give us a chance to flex our regex and refactoring muscles, so it should be fun! Let's get started.