Create an Application

We’ll use the Rails Composer tool to build a starter app. For this
tutorial, we’ll start with the rails-bootstrap example application.
Though you can build the starter app with RSpec automatically installed,
we’ll build it without RSpec, and then add RSpec manually so you’ll see
everything that is required to use RSpec.

To build the starter app, Rails 4.1 must be installed in your
development environment. Run the command:

$ rails new rails-bootstrap -m
https://raw.github.com/RailsApps/rails-composer/master/composer.rb -T

Be sure to add the -T flag to skip Test::Unit files that are not needed
for RSpec.