Use more generic test env flag

actionpack/lib/action_controller/dispatcher.rb

@@ -120,7 +120,7 @@ module ActionController
     def checkin_connections
       # Don't return connection (and peform implicit rollback) if this request is a part of integration test
       # TODO: This callback should have direct access to env
-      return if @request.key?("action_controller.test")
+      return if @request.key?("rack.test")
       ActiveRecord::Base.clear_active_connections!
     end
 

actionpack/lib/action_controller/failsafe.rb

@@ -11,7 +11,7 @@ module ActionController
       @app.call(env)
     rescue Exception => exception
       # Reraise exception in test environment
-      if env["action_controller.test"]
+      if env["rack.test"]
         raise exception
       else
         failsafe_response(exception)

actionpack/lib/action_controller/integration.rb

@@ -291,7 +291,7 @@ module ActionController
             "rack.multiprocess" => true,
             "rack.run_once"     => false,
 
-            "action_controller.test" => true
+            "rack.test" => true
           )
 
           (headers || {}).each do |key, value|