forms_controller.rb

class FormsController < ApplicationController
  def index
   respond_to do |format|
      format.html {render template: "shared/backbone", locals: {preloaded: {forms: all_forms}}}
      format.json {render json: all_forms}
    end
  end

  private

  def all_forms
    FormRepository.all(current_organization)
  end
end

forms_controller_spec.rb

require 'models/form_repository'
require 'controllers/forms_controller'

describe FormsController do
  let(:form) {stub}
  let(:responder) {stub.as_null_object}
  let(:organization) {stub}

  let(:controller) do
    controller = FormsController.new
    controller.stub!(current_organization: organization)
    controller
  end

  describe "#index" do
    it "finds all forms and renders them as json when json wanted" do
      expect_to_want(:json)
      FormRepository.should_receive(:all).with(organization).and_return([form])
      controller.should_receive(:render).with(json: [form])
      controller.index
    end
  end

  def expect_to_want(type)
    controller.should_receive(:respond_to).and_yield(responder)
    responder.should_receive(type).and_yield
  end
end

mock_application_controller.rb

class ApplicationController
  class << self
    def method_missing(meth, *args)
    end
  end

  def params
    @params ||= {}
  end

  def method_missing(meth, *args)
  end
end