thoughtbot/suspenders — comment on commit 7e06fe7a1ebc5f3eaeccde3dda7434bbef93aac4
File: lib/suspenders/generators/app_generator.rb line 89
By jferris:

What about when somebody tries to run it in a real application, though?
Unless they have all the gems in the Gemfile, it will fail. Not everything
should be a gem dependency, since several are optional.