Yes, we are dogfooding pretty hard! We release a bunch of times a day and every release goes through a suite of >130 Rainforest tests for regression. We also add tests for every new feature we release, so it keeps growing.
It was a cool thing to write tests for testing the test writing interface :) That's one "level deep" - out of curiosity I was playing with how deep it's possible to go and it turned out at 7 levels things get too small to really make sense (terminal within a terminal within a terminal etc.), but there's no inherent limit.
And we can do this because we work on the pixel level - even though the terminal is a canvas element and it'd be hard/impossible to work with it using the DOM, it doesn't really matter for KVM.
Do you test the new user path? Tried to create a free account with email, didn't get an email. Tried to register with GitHub, authorized rainforest in git, still can't log in.
Maybe someone in my organization already tried the free account or something but as a user I get no info at all. Just a unusable login page that looks like it needs some CI testing ;)