Run this command, replace gem_name
$ rails plugin new gem_name -T --mountable --dummy-path=spec/dummy # for namespaced mountable engine
$ rails plugin new gem_name -T --full --dummy-path=spec/dummy # for basic engine
Add the following to the Gemfile
gem "rspec-rails", "2.14.0.rc1"
gem "factory_girl_rails", "4.2.1"