Creating a new Rails 3 Application with Mongoid, RSpec, Cucumber and Shoulda

This article will work through creating a new Rails 3 application ready to start building a site using Mongoid, and testing it with Cucumber and RSpec.

I’m going to assume you’re familiar with the basics, and you’ve got a copy of Ruby 1.8.7 and MongoDB installed and running. If that’s not the case, go and get it setup using RVM or similar.

As much as I’d love to be using Ruby 1.9.2, ruby-debug doesn’t work with it yet, and I’m not about to give up my precious debugger.

Creating the Application

You’ll need to install the pre-release version (currently 3.0.0 beta 4) before we start:

# gem install rails --version "3.0.0.beta4"

Once that’s done, you can create a new application. We’re going to skip some of the default components, because we’ll be using alternatives.

# rails new example_app --skip-activerecord \
                        --skip-prototype \
                        --skip-testunit
create  
create  README
create  Rakefile
create  config.ru
... lots more create statements ...
create  tmp/pids
create  vendor/plugins
create  vendor/plugins/.gitkeep

Install the Gems

Once our application has been generated we need to specify the gems we’ll be using in the Gemfile, which is used by Bundler to manage dependencies.

In your application root, open up Gemfile and replace it with the following, which should be fairly self explanatory.

source "http://rubygems.org"

gem 'rails', '3.0.0.beta4'
gem 'mongoid', :git => 'git://github.com/durran/mongoid.git'
# C extension to improve MongoDB performance
gem 'bson_ext'

group :development do
  gem 'unicorn'
  gem 'ruby-debug'
end

group :test do
  gem 'capybara'
  gem 'cucumber-rails'
  gem 'rspec-rails', '>= 2.0.0.beta.12'
  gem 'factory_girl'
  gem 'mongoid-rspec', :require => false
end

And then run bundle install to install all the dependencies.

Install Mongoid

The next few steps are mostly just running generators, thanks to the fancy new integration available with Rails 3.

# rails g mongoid:config

Then open up config/mongoid.yml and make any changes neccesary for your machine. The defaults work for me when using a copy of Mongo installed using Homebrew.

At this point, when you generate a new model, you’ll get a Mongoid document rather then an ActiveRecord model.

Install RSpec

Installing RSpec is very similar:

# rails g rspec:install

Then insert the following after require ‘rspec/rails’ in spec/spec_helper.rb

require 'mongoid-rspec'

And this after the Rspec.configure line:

include Mongoid::Matchers

That’s it for vanilla RSpec. Nothing more to be done. If you run rake now you should see.

(in /Users/jon/Dropbox/example_app)
No examples matching ./spec/**/*_spec.rb could be found

Install Cucumber

We’re going to install Cucumber telling it to use Capybara so that we can test Javascript as well, and not to modify database.yml

rails g cucumber:install --capybara --skip-database

We’ll also need to provide it with a placeholder task for db:test:prepare, because it expects that to be present as well. If it’s not their, you’ll get the error Don’t know how to build task ‘db:test:prepare’. Put the following in lib/tasks/db.rake

namespace :db do
  namespace :test do
    task :prepare do
      # Placeholder for Cucumber
    end
  end
end

And the Cucumber environment needs changing to deal with ActiveRecord not being present as well. Edit features/support/env.rb and comment out or remove the line below.

Cucumber::Rails::World.use_transactional_fixtures = true

While you’re in there, remove the if statement around Database Cleaner’s setup so that the database is also emptied out for MongoDB.

# if defined?(ActiveRecord::Base)
  begin
    require 'database_cleaner'
    DatabaseCleaner.strategy = :truncation
  rescue LoadError => ignore_if_database_cleaner_not_present
  end
# end

Now that all that has been done, you should be able to run rake cucumber:ok and get this output:

Using the default profile...


0 scenarios
0 steps
0m0.000s

Testing Sugar

Now we’re going to add in Factory Girl to the test suite to make things that little bit more conveniant for us. It even comes with Cucumber steps to build models from factories.

Create a directory for factories. We’ll eventually fill this with a file for each model type, in the format model_name_factories.rb.

# mkdir spec/factories

And then require factory_girl and the factories for both RSpec and Cucumber.

In spec/spec_helper.rb, after you require mongoid-rspec

require 'factory_girl'
Dir.glob(Rails.root.join("spec", "factories", "*.rb").to_s).each do |f|
  require f
end

And in features/support/env.rb, after Capybara configuration the same, followed by:

require 'factory_girl/step_definitions'

Check out Thoughtbot’s article on the bundled Cucumber steps.

Bonus! jQuery

You may have noticed my call to —skip-prototype. That’s because we’re going to use jQuery instead.

curl http://github.com/rails/jquery-ujs/raw/master/src/rails.js > public/javascripts/rails.js

And then when you load jQuery, load rails.js as well, and you can use the standard Rails helpers for Javascript and it’ll all just work.

And Your Done

Thats it. You’re ready to rock and roll now.