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.

1 files changed, 4 insertions, 0 deletions

diff --git a/railties/test/railties/engine_test.rb b/railties/test/railties/engine_test.rb
index 7a047ef93a..4437e2c8af 100644
--- a/railties/test/railties/engine_test.rb
+++ b/railties/test/railties/engine_test.rb
@@ -1098,6 +1098,10 @@ YAML
 
       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