hectcastro/minitest-handler-cookbook — pull request #1 by ulfmagnetics (2012-06-02 17:06:28+00:00)
Title: Register spec type

I'm using the opscode omnibus installer and was running into the same issue as you (also filed at https://github.com/calavera/minitest-chef-handler/issues/21). I found that I had to explicitly install a newer version of minitest to get the register_spec_type method, since omnibus bundles v1.6.0 of minitest at this time.