[koliber]

I would beg to differ. As you've mentioned, there exists an official TLD suffix. However, de facto, .dev is the testing TLD. I've never seen .example or .invalid in real life. I've seen a tiny bit of .test. At every job that had a test dev, we used .dev. In many cases that decision was made by other developers. Judging by the comments here, and the article, it seems that many people have been using it.

A case can be made. How strong it will be remains to be seen. I hope Google can see the greater good in this. They have a lot of good will to win amongst the developer community.