1 files changed, 25 insertions, 10 deletions

diff --git a/actionpack/lib/action_controller/test_case.rb b/actionpack/lib/action_controller/test_case.rb
index 442ffd6d7c..700317614f 100644
--- a/actionpack/lib/action_controller/test_case.rb
+++ b/actionpack/lib/action_controller/test_case.rb
@@ -7,6 +7,24 @@ require 'action_controller/template_assertions'
 require 'rails-dom-testing'
 
 module ActionController
+  # :stopdoc:
+  class Metal
+    include Testing::Functional
+  end
+
+  module Live
+    # Disable controller / rendering threads in tests.  User tests can access
+    # the database on the main thread, so they could open a txn, then the
+    # controller thread will open a new connection and try to access data
+    # that's only visible to the main thread's txn.  This is the problem in #23483
+    remove_method :new_controller_thread
+    def new_controller_thread # :nodoc:
+      yield
+    end
+  end
+
+  # ActionController::TestCase will be deprecated and moved to a gem in Rails 5.1.
+  # Please use ActionDispatch::IntegrationTest going forward.
   class TestRequest < ActionDispatch::TestRequest #:nodoc:
     DEFAULT_ENV = ActionDispatch::TestRequest::DEFAULT_ENV.dup
     DEFAULT_ENV.delete 'PATH_INFO'
@@ -34,7 +52,7 @@ module ActionController
       self.session = session
       self.session_options = TestSession::DEFAULT_OPTIONS
       @custom_param_parsers = {
-        Mime[:xml] => lambda { |raw_post| Hash.from_xml(raw_post)['hash'] }
+        xml: lambda { |raw_post| Hash.from_xml(raw_post)['hash'] }
       }
     end
 
@@ -87,7 +105,7 @@ module ActionController
           when :url_encoded_form
             data = non_path_parameters.to_query
           else
-            @custom_param_parsers[content_mime_type] = ->(_) { non_path_parameters }
+            @custom_param_parsers[content_mime_type.symbol] = ->(_) { non_path_parameters }
             data = non_path_parameters.to_query
           end
         end
@@ -452,16 +470,16 @@ module ActionController
             parameters = nil
           end
 
-          if parameters.present? || session.present? || flash.present?
+          if parameters || session || flash
             non_kwarg_request_warning
           end
         end
 
-        if body.present?
+        if body
           @request.set_header 'RAW_POST_DATA', body
         end
 
-        if http_method.present?
+        if http_method
           http_method = http_method.to_s.upcase
         else
           http_method = "GET"
@@ -469,16 +487,12 @@ module ActionController
 
         parameters ||= {}
 
-        if format.present?
+        if format
           parameters[:format] = format
         end
 
         @html_document = nil
 
-        unless @controller.respond_to?(:recycle!)
-          @controller.extend(Testing::Functional)
-        end
-
         self.cookies.update @request.cookies
         self.cookies.update_cookies_from_jar
         @request.set_header 'HTTP_COOKIE', cookies.to_header
@@ -658,4 +672,5 @@ module ActionController
 
     include Behavior
   end
+  # :startdoc:
 end