There is no need to open AC::Base three times to setup tests.

actionpack/test/abstract_unit.rb

@@ -274,33 +274,20 @@ def assert_header(name, value)
   end
 end
 
-class ActionController::Base
-  def self.test_routes(&block)
-    routes = ActionDispatch::Routing::RouteSet.new
-    routes.draw(&block)
-    include routes.url_helpers
-  end
-end
-
-class ::ApplicationController < ActionController::Base
-end
-
-module ActionView
-  class TestCase
-    # Must repeat the setup because AV::TestCase is a duplication
-    # of AC::TestCase
-    setup do
-      @routes = SharedTestRoutes
-    end
-  end
-end
-
 module ActionController
   class Base
     include ActionController::Testing
-  end
+    # This stub emulates the Railtie including the URL helpers from a Rails application
+    include SharedTestRoutes.url_helpers
 
-  Base.view_paths = FIXTURE_LOAD_PATH
+    self.view_paths = FIXTURE_LOAD_PATH
+
+    def self.test_routes(&block)
+      routes = ActionDispatch::Routing::RouteSet.new
+      routes.draw(&block)
+      include routes.url_helpers
+    end
+  end
 
   class TestCase
     include ActionDispatch::TestProcess
@@ -311,9 +298,15 @@ class TestCase
   end
 end
 
-# This stub emulates the Railtie including the URL helpers from a Rails application
-module ActionController
-  class Base
-    include SharedTestRoutes.url_helpers
+class ::ApplicationController < ActionController::Base
+end
+
+module ActionView
+  class TestCase
+    # Must repeat the setup because AV::TestCase is a duplication
+    # of AC::TestCase
+    setup do
+      @routes = SharedTestRoutes
+    end
   end
 end