Making it easier to create and manage Test Users
developers.facebook.com/blog/post/527
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Today we are announcing the ability to create and add Test Users to your apps from the Developer Site. Test Users are invisible user accounts associated with an app created for the purpose of testing the functionality of that app. Test Users are not visible by others on Facebook; They can only be friends with other Test Users, but can still experience your app as a regular user. The programmatic interface to create a Test User has been available since November, but we have now built a simple user interface within the Developer App.