Fix railties_order when application object is passed

railites_order method, introduced in 40b19e0, had a bug that was causing
loading application instance twice in initializers if railties_order
already included application instance. So for example

    railties_order = [Foo::Engine, :main_app, Bar::Engine]

would result in such railties array:

    [MyApp::Application, Foo::Engine, MyAppApplication, Bar::Engine]

In order to fix it, we need to check for existence of application in
both railties_order and railties arrays.

2 files changed, 5 insertions, 1 deletions

diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 6d3349c61b..d92117f97e 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -188,7 +188,7 @@ module Rails
         end
 
         all = (railties.all - order)
-        all.push(self)   unless all.include?(self)
+        all.push(self)   unless (all + order).include?(self)
         order.push(:all) unless order.include?(:all)
 
         index = order.index(:all)
diff --git a/railties/test/railties/engine_test.rb b/railties/test/railties/engine_test.rb
index 400cae98b2..1a92f2f499 100644
--- a/railties/test/railties/engine_test.rb
+++ b/railties/test/railties/engine_test.rb
@@ -752,6 +752,10 @@ module RailtiesTest
 
       get("/assets/bar.js")
       assert_equal "// App's bar js\n;", last_response.body.strip
+
+      # ensure that railties are not added twice
+      railties = Rails.application.ordered_railties.map(&:class)
+      assert_equal railties, railties.uniq
     end
 
     test "railties_order adds :all with lowest priority if not given" do