Chef Zero is a simple, easy-install, in-memory Chef server that can be
useful for Chef Client testing and chef-solo-like tasks that require a
full Chef Server. It IS intended to be simple, Chef 11 compliant, easy
to run and fast to start. It is NOT intended to be secure, scalable,
performant or persistent. It does NO input validation, authentication
or authorization (it will not throw a 400, 401 or 403). It does not
save data, and will start up empty each time you start it.

Because Chef Zero runs in memory, it's super fast and lightweight.
This makes it perfect for testing against a "real" Chef Server without
mocking the entire Internet.