snippet.rb

### QUESTION::  Why does this behave in this way ??
#
# Summary:
# 
# When adding a Sinatra Extension with instance variables that are essentially buffers during the request 
# the new values does NOT get added to the instance variable.
# 
# Key Issues:
# 
# * Compare using 'app' vs '@app' in the tests below.
# * Why does the content not get output during the request? 
# 
# 
# If I'm doing something wrong below, please fork, show & let me know.



require 'rubygems'
require 'sinatra/base'
require 'test/spec' # sorry, using test/spec since rspec via TextMate don't work in single file
require 'rack/test' # using v0.4.0

module Assets
  # this should hold all custom css added during the request.
  @kematzy_assets_custom_css = []
  attr_accessor :kematzy_assets_custom_css
  
  def add_custom_css(css) 
    @kematzy_assets_custom_css ||= []
    @kematzy_assets_custom_css << css
  end
  
  def custom_css
    @kematzy_assets_custom_css
  end
  
end #/module Assets

##===================================================

## Sinatra Extension
module Sinatra
  
  module Kematzy
    
    module Helpers
      include Assets
      
    end #/module Helpers
    
    def self.registered(app)
      app.helpers Kematzy::Helpers
    end
    
  end #/module Kematzy
  
end #/module Sinatra

##===================================================

## Sinatra App
class Dummy < Sinatra::Base
  register(Sinatra::Kematzy)
  
  set :public, 'public'
  set :views, 'views'
  
  get '/' do
    erb("<style>#{custom_css}</style>")
  end
  
end

##===================================================

class Test::Unit::TestCase 
  include Rack::Test::Methods
  def app ; Dummy.new() ; end
  def setup ; Sinatra::Base.set :environment, :test ; end
end

##===================================================

describe "Sinatra::Kematzy::Helpers" do 
  
  describe "should add custom css and store it in the @kematzy_assets_custom_css instance var" do
    
    describe "WHY does using 'app' NOT work ?" do 
      
      it "should store it in the @kematzy_assets_custom_css" do 
        app.add_custom_css('custom')
        app.kematzy_assets_custom_css.should == ['custom']  # => returns NIL
      end
      
      it "should return the custom css via the #custom_css method" do 
        app.add_custom_css('custom')
        app.custom_css.should == ['custom']  # => returns NIL
      end
      
    end 
    
    describe "WHY does using '@app' work" do 
      
      before(:each) do 
        @app = app  # just making app and instance variable 
      end
      
      it "should store it in the @kematzy_assets_custom_css" do 
        @app.add_custom_css('custom')
        @app.kematzy_assets_custom_css.should == ['custom']  # => Works as expected
      end
      
      it "should return the custom css via the #custom_css method" do 
        @app.add_custom_css('custom')
        @app.custom_css.should == ['custom']  # => Works as expected
      end
      
    end #/ WHY does @app work
    
    it "should return the custom css through the response" do 
      #  NOTE:: this test passes IF I use 'sinatra/test' instead of 'rack/test'.
      #  (obviously with the required code changes)
      
      get '/'
      last_response.body.should == '<style>custom</style>' # => does not work :(
    end
    
  end
  
end #/ Sinatra::Kematzy::Helpers