Fix generators to help with ambiguous `ApplicationController` issue

In development mode, dependencies are loaded dynamically at runtime,
using `const_missing`. Because of that, when one of the constants is
already loaded and `const_missing` is not triggered, user can end up
with unexpected results.

Given such file in an Engine:

```ruby
module Blog
  class PostsController < ApplicationController
  end
end
```

If you load it first, before loading any application files, it will
correctly load `Blog::ApplicationController`, because second line will
hit `const_missing`. However if you load `ApplicationController` first,
the constant will be loaded already, `const_missing` hook will not be
fired and in result `PostsController` will inherit from
`ApplicationController` instead of `Blog::ApplicationController`.

Since it can't be fixed in `AS::Dependencies`, the easiest fix is to
just explicitly load application controller.

closes #6413

1 files changed, 12 insertions, 5 deletions

diff --git a/railties/test/generators/namespaced_generators_test.rb b/railties/test/generators/namespaced_generators_test.rb
index c495258343..903465392d 100644
--- a/railties/test/generators/namespaced_generators_test.rb
+++ b/railties/test/generators/namespaced_generators_test.rb
@@ -20,8 +20,14 @@ class NamespacedControllerGeneratorTest < NamespacedGeneratorTestCase
 
   def test_namespaced_controller_skeleton_is_created
     run_generator
-    assert_file "app/controllers/test_app/account_controller.rb", /module TestApp/, /  class AccountController < ApplicationController/
-    assert_file "test/functional/test_app/account_controller_test.rb", /module TestApp/, /  class AccountControllerTest/
+    assert_file "app/controllers/test_app/account_controller.rb",
+                /require "test_app\/application_controller"/,
+                /module TestApp/,
+                /  class AccountController < ApplicationController/
+
+    assert_file "test/functional/test_app/account_controller_test.rb",
+                /module TestApp/,
+                /  class AccountControllerTest/
   end
 
   def test_skipping_namespace
@@ -227,9 +233,10 @@ class NamespacedScaffoldGeneratorTest < NamespacedGeneratorTestCase
     end
 
     # Controller
-    assert_file "app/controllers/test_app/product_lines_controller.rb" do |content|
-      assert_match(/module TestApp\n  class ProductLinesController < ApplicationController/, content)
-    end
+    assert_file "app/controllers/test_app/product_lines_controller.rb",
+                /require "test_app\/application_controller"/,
+                /module TestApp/,
+                /class ProductLinesController < ApplicationController/
 
     assert_file "test/functional/test_app/product_lines_controller_test.rb",
                 /module TestApp\n  class ProductLinesControllerTest < ActionController::TestCase/