for use with rspec-rails controller specs; avoids duplicate actions that basically differ only in the controller action. note the required spec_helper update

request_launching.rb

# streamlines request launching to remove duplication
#
# enables this setup:
# describe SomeController do
#   describe :index do
#     it 'works' do
#       should do_something
#       launch_request
#       response.code.should eq('200')
#     end
#   end
# end
#
# accepts parameters, session data, flash data like so:
# launch_request :params => {}, :session => {}, :flash => {}
#
# uses POST, PUT, and DELETE for create, update, and destroy requests, respectively, GET otherwise
# set @method in a before(:all) block to override this, like so:
# before(:all){@method = :post}
#
# doesn't care where in the hierarchy the action verb is, thus enabling nested shared example groups
#
# verifies previously set expectations, thus state verification takes place _after_ behaviour verification
# BEWARE: this means calling launch_request twice leads to exceptions
#
# the variant launch_request_without_super makes the action call ignore super
# that is useful in case the application's actions inherit from a gem's actions
# specifying or stubbing what the gem does can be too much hassle
#
#
# put this in spec_helper:
# RSpec.configure do |config|
#   config.include RequestLaunching, :type => :controller
# end
#
module RequestLaunching
  def launch_request(options={})
    method, action = method_and_action
    kick_off method, action, options
  end

  def launch_request_without_super(options={}, &block)
    method, action = method_and_action

    described_class.ancestors[1].send(:alias_method, :stubbed_out_super, action)
    described_class.ancestors[1].send(:define_method, action, block||lambda{})

    kick_off method, action, options

    described_class.ancestors[1].send(:alias_method, action, :stubbed_out_super)
  end

  # shortcuts
  alias launch launch_request
  alias launch_request_with_stubbed_super launch_request_without_super
  alias launch_without_super launch_request_without_super
  alias launch_with_stubbed_super launch_request_without_super

  private

  def kick_off(method, action, options)
    # prepare data for the launch
    parameters = (@params ||{}).merge(options[:params] ||{}) unless options[:params].nil? and @params.nil?
    session = (@session ||{}).merge(options[:session] ||{}) unless options[:session].nil? and @session.nil?
    flash = (@flash ||{}).merge(options[:flash] ||{}) unless options[:flash].nil? and @flash.nil?

    # launch the request with the given options, merged into the related instance variables
    if options[:xhr] || @xhr
      xml_http_request method,
        action,
        parameters,
        session,
        flash
    else
      __send__ method,
        action,
        parameters,
        session,
        flash
    end

    # verify behaviour expectations
    RSpec::Mocks.verify
  end

  def method_and_action
    focus = self.class.instance_variable_get('@metadata')

    # find the nearest action verb
    while focus = focus[:example_group] do
      action = focus[:description] and break if described_class.action_methods.include?(focus[:description])
    end

    raise "you need to specify an action of #{described_class}" unless action

    # find the method corresponding to the action
    method = @method || {
      'create' => :post,
      'update' => :put,
      'destroy' => :delete
    }[action] || :get

    return method, action
  end
end