The supporting code for my blog entry: "Get out of my Controller! And from Active Record, too!"

get_out_of_my_controller_spec.rb

module ActiveRecord; class Base; end; end

# The AR Models Rails give you
class User < ActiveRecord::Base
  # These fields are defined dynamically by ActiveRecord
  attr_accessor :id, :full_name
end

class Discussion < ActiveRecord::Base
  # These fields are defined dynamically by ActiveRecord
  attr_accessor :id, :title, :body, :comments
end

class Comment < ActiveRecord::Base
  # These fields are defined dynamically by ActiveRecord
  attr_accessor :id, :text, :entered_by
end

# The DTO models I use in my view
module DTO
  class User
    attr_reader :source_object, :id, :full_name
    attr_accessor :comments
    def initialize(source_object)
      @source_object = source_object
      @id = source_object.id
      @full_name = source_object.full_name
    end
  end

  class Discussion
    attr_reader :source_object, :id, :title, :body, :comments
    def initialize(source_object)
      @source_object = source_object
      @id = source_object.id
      @title = source_object.title
      @body = source_object.body
      @comments = ::DTO::Comment.initialize_collection(source_object.comments)
    end
  end

  class Comment
    attr_reader :source_object, :id, :text, :entered_by
    def initialize(source_object)
      @source_object = source_object
      @id = source_object.id
      @text = source_object.text
      @entered_by = @source_object.entered_by
    end

    def self.initialize_collection(source_objects)
      source_objects.map do |source_object|
        self.new(source_object)
      end
    end
  end
end

# Services used in the app
module Service
  class FindsDiscussion
    def self.for(id)
      # This is very high level
      ::DTO::Discussion.new(Discussion.find(id))
    end
  end

  class FindsUsers
    def self.all
      User.all.map { |user| ::DTO::User.new(user) }
    end
  end

  class SetsComments
    def self.on_users(users, comments)
      users.each do |user|
        user.comments = comments.select do |comment|
          user.source_object.id == comment.source_object.entered_by
        end
      end
    end
  end
end

class ApplicationController; end

class DiscussionsController < ApplicationController
  attr_reader :users, :discussion

  def index
    @users = Service::FindsUsers.all
    @discussion = Service::FindsDiscussion.for(params[:id])
    Service::SetsComments.on_users(@users, @discussion.comments)
  end
end

describe DiscussionsController do
  subject { DiscussionsController.new }

  it { should respond_to :index }

  specify "index retrieves all the data for display" do
    subject.stub(:params => {:id => 12})
    discussion_dto = DTO::Discussion.new(Factory::ForDiscussion.make_one)
    Service::FindsDiscussion.stub(:for).and_return discussion_dto

    user_dummies = Factory::ForUser.make_two
    user_dtos = user_dummies.map { |user_dummy| DTO::User.new(user_dummy) }
    Service::FindsUsers.stub(:all).and_return user_dtos

    Service::SetsComments.stub(:on_users).with(user_dtos, discussion_dto.comments)
    # call the method under test
    subject.index
  end
end

# To keep the examples simple, I am not using FactoryGirl or Machinist
module Factory
  class ForUser
    def self.make_two
      user1 = User.new
      user1.id = 2
      user1.full_name = 'User 1'

      user2 = User.new
      user2.id = 54
      user2.full_name = 'User 2'

      [user1, user2]
    end
  end

  class ForDiscussion
    def self.make_one
      discussion = Discussion.new
      discussion.id = 12
      discussion.title = 'This is the discussion title'
      discussion.body = 'This is the discussion body. I make it a little bit longer.'
      discussion.comments = ForComment.make_two
      discussion
    end
  end

  class ForComment
    def self.make_two
      comments = []
      comments << make_one
      comments << make_one
      comments.last.id = 33
      comments.last.entered_by = 3
      comments
    end

    def self.make_one
      comment = Comment.new
      comment.id = 32
      comment.text = 'This is the comment test.'
      comment.entered_by = 2
      comment
    end
  end
end