It is easy enough to debug specs on by one. For this you just run the ruby file that contains the spec with ruby-debug instead of ruby:
rdebug spec/rur_spec.rb
But when running via rake, you can’t do this. A simple solution is to add these lines in the spec file you want to debug (or in spec_helper.rb):
require_library_or_gem 'ruby-debug'
Debugger.start
And you are in business…
This is a good debugging technique. Makes everything much simpler.