Don't load ActionSystemTest in production

By moving to the TestUnit Railtie, and doing the file requirement
inside the onload call we can avoid loading ActionSystemTest in
production and load it in the test env.

This is important for performance reasons - loading up unnecessary files
and object is expensive, especially when they should never be used in
production.

4 files changed, 12 insertions, 20 deletions

diff --git a/actionsystemtest/lib/action_system_test.rb b/actionsystemtest/lib/action_system_test.rb
index 4a80e34695..18b992a3ca 100644
--- a/actionsystemtest/lib/action_system_test.rb
+++ b/actionsystemtest/lib/action_system_test.rb
@@ -50,8 +50,6 @@ require "action_system_test/driver_adapter"
 module ActionSystemTest
   include ActionSystemTest::TestHelper
   include ActionSystemTest::DriverAdapter
-
-  ActiveSupport.run_load_hooks(:system_testing, self)
 end
 
 class ActionSystemTestCase < ActionDispatch::IntegrationTest
diff --git a/actionsystemtest/lib/action_system_test/railtie.rb b/actionsystemtest/lib/action_system_test/railtie.rb
deleted file mode 100644
index 6f4fe1b993..0000000000
--- a/actionsystemtest/lib/action_system_test/railtie.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require "action_system_test"
-
-module ActionSystemTest
-  # = System Testing Railtie
-  class Railtie < Rails::Railtie # :nodoc:
-    config.system_testing = ActiveSupport::OrderedOptions.new
-
-    initializer "system_testing.set_configs" do |app|
-      options = app.config.system_testing
-      options.driver ||= ActionSystemTest.default_driver
-
-      ActiveSupport.on_load(:system_testing) do
-        options.each { |k,v| send("#{k}=", v) }
-      end
-    end
-  end
-end
diff --git a/railties/lib/rails/all.rb b/railties/lib/rails/all.rb
index 2cc33ceb5e..7606ea0e46 100644
--- a/railties/lib/rails/all.rb
+++ b/railties/lib/rails/all.rb
@@ -9,7 +9,6 @@ require "rails"
   action_cable/engine
   rails/test_unit/railtie
   sprockets/railtie
-  action_system_test/railtie
 ).each do |railtie|
   begin
     require railtie
diff --git a/railties/lib/rails/test_unit/railtie.rb b/railties/lib/rails/test_unit/railtie.rb
index d3f52e8008..694c8d92b1 100644
--- a/railties/lib/rails/test_unit/railtie.rb
+++ b/railties/lib/rails/test_unit/railtie.rb
@@ -20,6 +20,18 @@ module Rails
       }
     end
 
+    config.system_testing = ActiveSupport::OrderedOptions.new
+
+    initializer "system_testing.set_configs" do |app|
+      ActiveSupport.on_load(:active_support_test_case) do
+        require "action_system_test"
+
+        options = app.config.system_testing
+        options.driver ||= ActionSystemTest.default_driver
+        options.each { |k, v| ActionSystemTest.send("#{k}=", v) }
+      end
+    end
+
     rake_tasks do
       load "rails/test_unit/testing.rake"
     end