Testing root server down code

The last time all the root servers were down was June 28 1985. On June 29 1985 there was a flurry of messages about adding root server down code to the various DNS implementations of the day. Apparently, some of the software had a poor response to all root servers being unreachable, and spun out of control. Has anyone tested modern DNS code (Microsoft and BIND to name two) for this condition recently? I haven't, hence my question.