Jason McCreary has a post on his site where he's officially accepted a challenge made by Adam Wathan during the Laracon Online conference and how he went about solving it.

Last week at Laracon Online Adam Wathan gave a talk entitled “Lies you’ve been told about testing”. Following the talk, Adam posted a challenge. Amid Adam’s post, he makes a single claim and presents a challenge.

The challenge was to write a unit test for the three provided class implementations in isolation. The claim is that isolated unit testing is incompatible with Test Driven Development (TDD). He talks about the other phases of TDD outside of the "refactor" step ("red" and "green") and how he would apply those to the steps leading to a complete refactor. He also talks briefly about testing styles and what would need to change to complete the process on both the code and the test side.