Engine routes for controllers

Controller specs can specify the routeset that will be used for the example group. This is most useful when testing Rails engines.

Specify engine routes

Given a file named "spec/controllers/widgets_controller_spec.rb" with:

require "rails_helper"

# A very simple Rails engine
module MyEngine
  class Engine < ::Rails::Engine
    isolate_namespace MyEngine
  end

  Engine.routes.draw do
    resources :widgets, :only => [:show] do
      get :random, :on => :collection
    end
  end

  class WidgetsController < ::ActionController::Base
    def random
      @random_widget = Widget.all.shuffle.first
      redirect_to widget_path(@random_widget)
    end

    def show
      @widget = Widget.find(params[:id])
      render :text => @widget.name
    end
  end
end

RSpec.describe MyEngine::WidgetsController, type: :controller do
  routes { MyEngine::Engine.routes }

  it "redirects to a random widget" do
    widget1 = Widget.create!(:name => "Widget 1")
    widget2 = Widget.create!(:name => "Widget 2")

    get :random
    expect(response).to be_redirect
    expect(response).to redirect_to(assigns(:random_widget))
  end
end

When I run rspec spec

Then the examples should all pass.