Engine sets routes as default rack endpoint if no endpoint was given

2 files changed, 5 insertions, 6 deletions

diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index a4cdc7306f..a21b560084 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -103,10 +103,6 @@ module Rails
       super
     end
 
-    def routes
-      @routes ||= ActionDispatch::Routing::RouteSet.new
-    end
-
     def railties
       @railties ||= Railties.new(config)
     end
diff --git a/railties/lib/rails/engine.rb b/railties/lib/rails/engine.rb
index 9a8dd8e8d4..c0607950b5 100644
--- a/railties/lib/rails/engine.rb
+++ b/railties/lib/rails/engine.rb
@@ -152,18 +152,21 @@ module Rails
     end
 
     def app
-      raise "You can't use Engine as rack application without providing valid rack endpoint" unless endpoint
       @app ||= config.middleware.build(endpoint)
     end
 
     def endpoint
-      self.class.endpoint
+      self.class.endpoint || routes
     end
 
     def call(env)
       app.call(env)
     end
 
+    def routes
+      @routes ||= ActionDispatch::Routing::RouteSet.new
+    end
+
     def initializers
       initializers = []
       railties.all { |r| initializers += r.initializers }