This includes rspec-rails in development mode so that we have access to RSpecspecific generators, and it includes it in test mode in order to run the tests. We don’t have to install RSpec itself because it is a dependency of rspec-rails and will thus be installed automatically. We also include the Capybara gem, which allows us to simulate a user’s interaction with the sample application using a natural English-like syntax.1 As in Chapter 2, we also must include the PostgreSQL gem in production for deployment to Heroku:

  Heroku recommends against using different databases in development and production, but for the sample application it won’t make any difference, and SQLite is much easier than PostgreSQL to install and configure. Installing and configuring PostgreSQL on your local machine is left as an exercise (Section 3.5).

To install and include the new gems, we run bundle install:

  As in Chapter 2, we suppress the installation of production gems using the option --without production. This is a ‘‘remembered option,’’ which means that we don’t have to include it in future invocations of Bundler. Instead, we can write simply bundle install. 2

Next, we need to configure Rails to use RSpec in place of Test::Unit. This can be accomplished with rails generate rspec:install:

If your system complains about the lack of a JavaScript runtime, visit the execjs page at GitHub for a list of possibilities. I particularly recommend installing Node.js.