Add missing support of Rails.application.config.action_controller.relative_url_root (#4146)

* Add Devise::FailureApp#{relative_url_root, relative_url_root?}

Also support missing action_controller.relative_url_root configuration.

* Dry assignment of relative_url_root

Also this commit adds support for
Rails.application.config.action_controller.relative_url_root

lib/devise/failure_app.rb

@@ -50,13 +50,11 @@ module Devise
     end
 
     def recall
-      config = Rails.application.config
-
-      header_info = if config.try(:relative_url_root)
-        base_path = Pathname.new(config.relative_url_root)
+      header_info = if relative_url_root?
+        base_path = Pathname.new(relative_url_root)
         full_path = Pathname.new(attempted_path)
 
-        { "SCRIPT_NAME" => config.relative_url_root,
+        { "SCRIPT_NAME" => relative_url_root,
           "PATH_INFO" => '/' + full_path.relative_path_from(base_path).to_s }
       else
         { "PATH_INFO" => attempted_path }
@@ -144,11 +142,7 @@ module Devise
 
       opts[:format] = request_format unless skip_format?
 
-      config = Rails.application.config
-
-      if config.respond_to?(:relative_url_root) && config.relative_url_root.present?
-        opts[:script_name] = config.relative_url_root
-      end
+      opts[:script_name] = relative_url_root if relative_url_root?
 
       router_name = Devise.mappings[scope].router_name || Devise.available_router_name
       context = send(router_name)
@@ -252,5 +246,17 @@ module Devise
     def request_format
       @request_format ||= request.format.try(:ref)
     end
+
+    def relative_url_root
+      @relative_url_root ||= begin
+        config = Rails.application.config
+
+        config.try(:relative_url_root) || config.action_controller.try(:relative_url_root)
+      end
+    end
+
+    def relative_url_root?
+      relative_url_root.present?
+    end
   end
 end

test/failure_app_test.rb

@@ -131,6 +131,24 @@ class FailureTest < ActiveSupport::TestCase
       end
     end
 
+    if Rails.application.config.action_controller.respond_to?(:relative_url_root)
+      test "returns to the default redirect location considering action_controller's relative url root" do
+        swap Rails.application.config.action_controller, relative_url_root: "/sample" do
+          call_failure
+          assert_equal 302, @response.first
+          assert_equal 'http://test.host/sample/users/sign_in', @response.second['Location']
+        end
+      end
+
+      test "returns to the default redirect location considering action_controller's relative url root and subdomain" do
+        swap Rails.application.config.action_controller, relative_url_root: "/sample" do
+          call_failure('warden.options' => { scope: :subdomain_user })
+          assert_equal 302, @response.first
+          assert_equal 'http://sub.test.host/sample/subdomain_users/sign_in', @response.second['Location']
+        end
+      end
+    end
+
     test 'uses the proxy failure message as symbol' do
       call_failure('warden' => OpenStruct.new(message: :invalid))
       assert_equal 'Invalid Email or password.', @request.flash[:alert]