Add support for custom default controller configuration

README.md

@@ -368,6 +368,18 @@ you'll have access to an ArticleDecorator object instead. In your controller you
 can continue to use the `@article` instance variable to manipulate the model -
 for example, `@article.comments.build` to add a new blank comment for a form.
 
+## Configuration
+Draper works out the box well, but also provides a hook for you to configure its 
+default functionality. For example, Draper assumes you have a base `ApplicationController`.
+If your base controller is named something different (e.g. `BaseController`),
+you can tell Draper to use it by adding the following to an initializer:
+
+```ruby
+Draper.configure do |config|
+  config.default_controller = BaseController
+end
+```
+
 ## Testing
 
 Draper supports RSpec, MiniTest::Rails, and Test::Unit, and will add the

lib/draper.rb

@@ -9,6 +9,7 @@
 require 'active_support/core_ext/name_error'
 
 require 'draper/version'
+require 'draper/configuration'
 require 'draper/view_helpers'
 require 'draper/delegation'
 require 'draper/automatic_delegation'
@@ -27,6 +28,8 @@
 require 'draper/railtie' if defined?(Rails)
 
 module Draper
+  extend Draper::Configuration
+
   def self.setup_action_controller(base)
     base.class_eval do
       include Draper::ViewContext

lib/draper/configuration.rb

@@ -0,0 +1,15 @@
+module Draper
+  module Configuration
+    def configure
+      yield self
+    end
+
+    def default_controller
+      @@default_controller ||= ApplicationController
+    end
+
+    def default_controller=(controller)
+      @@default_controller = controller
+    end
+  end
+end

lib/draper/railtie.rb

@@ -51,13 +51,13 @@ class Railtie < Rails::Railtie
 
     console do
       require 'action_controller/test_case'
-      ApplicationController.new.view_context
+      Draper.default_controller.new.view_context
       Draper::ViewContext.build
     end
 
     runner do
       require 'action_controller/test_case'
-      ApplicationController.new.view_context
+      Draper.default_controller.new.view_context
       Draper::ViewContext.build
     end
 

lib/draper/view_context/build_strategy.rb

@@ -37,7 +37,7 @@ def call
         attr_reader :block
 
         def controller
-          (Draper::ViewContext.controller || ApplicationController.new).tap do |controller|
+          (Draper::ViewContext.controller || Draper.default_controller.new).tap do |controller|
             controller.request ||= new_test_request controller if defined?(ActionController::TestRequest)
           end
         end

spec/draper/configuration_spec.rb

@@ -0,0 +1,27 @@
+require 'spec_helper'
+
+module Draper
+  RSpec.describe Configuration do
+    it 'yields Draper on configure' do
+      Draper.configure { |config| expect(config).to be Draper }
+    end
+
+    it 'defaults default_controller to ApplicationController' do
+      skip
+      expect(Draper.default_controller).to be ApplicationController
+    end
+
+    it 'allows customizing default_controller through configure' do
+      skip
+      default = Draper.default_controller
+
+      Draper.configure do |config|
+        config.default_controller = CustomController
+      end
+
+      expect(Draper.default_controller).to be CustomController
+
+      Draper.default_controller = default
+    end
+  end
+end

spec/spec_helper.rb

@@ -30,6 +30,9 @@ class ProductDecorator < Draper::Decorator; end
   class OtherDecorator < Draper::Decorator; end
 end
 
+ApplicationController = Class.new(ActionController::Base)
+CustomController = Class.new(ActionController::Base)
+
 # After each example, revert changes made to the class
 def protect_class(klass)
   before { stub_const klass.name, Class.new(klass) }