Coming from a Ruby on Rails background, it’s common place to see the Gemfile declarations in logical groups. This ensures your gems only get required in the environment they are needed.

A similar setup can be achieved in RubyMotion by tweaking your Gemfile and Rakefile.

In your Gemfile:

source "https://rubygems.org"
gem 'rake'
gem 'motion-cocoapods'

group :spec do
  gem 'motion-redgreen'
end

In your Rakefile:

if ARGV.join(' ') =~ /spec/
  Bundler.require :default, :spec
else
  Bundler.require
end

Thanks to the TinyMon application where I first saw this setup.