Testing before_filter in controller spec

testing_before_filter_in_controller_spec.rb

require 'rails_helper'

RSpec.describe MyController do
  describe 'GET #any_action' do
    controller do
      def any_action
        head :ok
      end
    end

    before do
      routes.draw { get 'testing' => 'my_controller#any_action' }
    end

    it 'is protected by a before filter' do
      get :any_action

      # expect side effect of before filter
    end
  end
end