Technical
How To Test Application Controller

Its very important to be able to test application_controller.rb since by default its sort of left out by windows but many people put lots of code there ( so am I)

How to setup you your test case.

create a test/functional/application_controller_test.rb file with following.

require File.dirname(__FILE__) + '/../test_helper'
require 'application'
require 'mocha'

# Re-raise errors caught by the controller.
class ApplicationController; def rescue_action(e) raise e end; end

class ApplicationControllerTest <Test::Unit::TestCase

  def setup
    @controller = ApplicationController.new
    @request    = ActionController::TestRequest.new
    @response   = ActionController::TestResponse.new
  end 

  #Sample Test 
  def test_that_test_can_get
    assert_nothing_raised{get :index}
  end

end

This way you’ll be able to use regular functional testing way calling your actions ( or methods of the application controller class). Also, you’ll be able to check you sessions, flashes e.t.c that will not be accessible other wise.

How to bypass MissingTemplate exception.

Sometimes I store filters that are used in many other controllers in the application controller for reusability. Filter, due to its nature does not render anything, so when you call it by get you will get missing template error. So i used assert_raises to show to other developers that this is something that will popup if filter called the way of get, but tests would pass normally.

  assert_raises(ActionController::MissingTemplate){get :set_legal_entity_id_session_if_current_is_blank}