Gem Extraction Cheat Sheet

Setup the Gem

1. bundle gem gem_name
2. edit gem_name.gemspec

  # ...
  gem.add_dependency "rails", ">= 3.2"
  gem.add_dependency "jquery-rails"

  gem.add_development_dependency 'sass-rails'
  gem.add_development_dependency 'coffee-rails'

  gem.add_development_dependency "rake"
  gem.add_development_dependency "bundler"
  gem.add_development_dependency "rspec-rails", ">= 2.8.0"
  gem.add_development_dependency "guard", "1.0.1"
  gem.add_development_dependency "nokogiri", ">= 1.5.0"
  gem.add_development_dependency "capybara"
  gem.add_development_dependency 'rspec-rails', '2.10.0'
  gem.add_development_dependency 'guard-rspec', '0.5.5'

  gem.add_development_dependency 'execjs'
  gem.add_development_dependency 'therubyracer'

1. bundle install
2. edit Rakefile:

require 'bundler/gem_tasks'
require 'rspec/core/rake_task'
RSpec::Core::RakeTask.new( :spec )
task default: :spec

1. edit lib/gem_name/version.rb (add .alpha)
2. create spec/spec_helper.rb

require 'gem_name'

1. edit README.md

Transfer code

• Copy the specs into the gem
• Copy the code into the gem
• ActiveRecord integration: see:
  • https://github.com/fiedl/acts_as_paranoid_dag/tree/master/spec
  • https://github.com/fiedl/acts_as_paranoid_dag/blob/master/acts_as_paranoid_dag.gemspec

Model Additions

• module GemName::ModelAdditions

  # lib/gem_name/model_additions.rb
  module GemName
    module ModelAdditions
      def acts_as_something
      end
    end
  end
  ActiveRecord::Base.extend GemName::ModelAdditions

• require that file in lib/gem_name.rb
• instead of direct ActiveRecord::Base extension, may use railtie:

# lib/gem_name/railtie.rb
module GemName
  class Railtie < Rails::Railtie
    initializer 'gem_name.model_additions' do
      ActiveSupport.on_load :active_record do
        extend ModelAdditions
      end 
    end
  end 
end

• add to lib/gem_name.rb:

require "spec_name/railtie" if defined? Rails

Adding a Test App

• add the test app to a test_app folder:

~/rails/gem_name$ rails new test_app

• require the test_app's environment in the specs, e.g. in the spec/spec_helper.rb

require File.expand_path('../../test_app/config/environment', __FILE__)

• configure javascript engine in spec/spec_helper.rb

RSpec.configure do |config|
  # ...
  Capybara.javascript_driver = :webkit
end

Publish the Test App at Heroku

• Add pg to the Gemfile:

gem 'sqlite3', group: :development
gem 'pg', group: :production

• Upload to heroku

$ cd test_app
$ git init
$ git add .
$ git commit -m "initial commit"
$ heroku create --stack cedar
$ heroku rename gem-name-test-app
$ git push heroku master
$ heroku run rake db:migrate  # if database needed

Test the Gem Locally

• add it to the Gemfile of some test app:

gem 'gem_name', path: 'path/to/gem'

Push the Gem to Github

• add files to local repository if not done, yet.

$ cd gem_name
$ git add .
$ git commit -m "initial commit."

• Create repository "gem_name" on http://github.com
• Push it:

$ git remote add origin [email protected]:your_git_user_name/gem_name.git
$ git push -u origin master

• in the Gemfile:

gem 'gem_name', git: 'git://github.com/your_git_user_name/gem_name.git'

Publish Gem

• Version number in lib/gem_name/version.rb
• Changelog
• Commit changes: e.g. with message: release v0.0.1
• Push it to http://rubygems.org:

$ rake release

• now remove git option from Gemfile
• bump version number in lib/gem_name/version.rb

Continuous Integration With Travis-CI

• sign in on http://travis-ci.org
• go to 'Profile' and turn on the switch of the corresponding github repository
• get image-url from the status page of the current build

Modify Travis for Use With JavaScript and Database

# .travis.yml
env: "RAILS_ENV=test DISPLAY=:99.0"
before_script:
  - "sh -c 'cd test_app && bundle && bundle exec rake db:drop db:migrate'"
  - "sh -e /etc/init.d/xvfb start"

Trouble Shooting

• add rake as an development dependency
• only test in ruby 1.9: Add file .travis.yml:

rvm:
  - 1.9.3

Code Documentation

• just add the github repository on http://rubydoc.info
• link to that from the README

Literature

• See, for example, Railscasts #301