title: testing rails engine generator with rspec
body: <p>I create a simpe gem wich include a install generator, generator works fine but now I want to test it using rspec, I foud this  <a href="https://github.com/sinisterchipmunk/genspec">gem</a>, and try to test my generator, my spec code is: </p>
  
  <pre><code>require 'genspec'
  require 'rosalie'
  
  describe :install_generator do
  
    it "should generate model" do
      subject.should generate("message.rb")
    end
  end
  </code></pre>
  
  <p>rosalie is the name of may gem, now when I run it I got an error:
  /stuff/work/my_projects/rosalie/lib/rosalie/engine.rb:2:in `': uninitialized constant Rosalie::Rails (NameError)</p>
  
  <p>my engine.rb code is:</p>
  
  <pre><code>module Rosalie
    class Engine &lt; Rails::Engine
  
      initializer "rosalie.models.messageable" do
        ActiveSupport.on_load(:active_record) do
          include Rosalie::Models::Messageable
        end
      end
    end
  end
  </code></pre>
  
  <p>anybody can help me with this problem?</p>