You'll be playing the game against other testers, and then sharing feedback with the dev team. (gonintendo.com)
Example resumes in this field show such skills as documenting issues and experiences with gameplay for the development team, and assisting other testers with troubleshooting issues on their platform. (jobhero.com)
From what other people are saying it would seem John may well be out on his own again on this one, given how other testers are raving about this car re-writing the rule books, oddly much like the F1 did... (evo.co.uk)