From 39b538e86bbae41fe7b4c90821ba882533543baa Mon Sep 17 00:00:00 2001
From: Jean Boussier <jean.boussier@gmail.com>
Date: Tue, 9 Apr 2024 16:36:01 +0200
Subject: [PATCH] Avoid loading ActionController::TestCase in production

Ref: https://github.com/Shopify/active_model_serializers/pull/3

> By referencing that object, it brings in all of the patches defined
> in `ActionController::TestCase` to the development and production
> environment, including behaviours like disabling the threading
> implementation of `ActionController::Live`
---
 .github/workflows/ci.yml        |  1 +
 lib/active_model_serializers.rb | 14 ++++++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 055e50b94..a32a8cc87 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -75,3 +75,4 @@ jobs:
           bundle exec rake
         env:
           RAILS_VERSION: ${{ matrix.rails-version }}
+          RAILS_ENV: test
diff --git a/lib/active_model_serializers.rb b/lib/active_model_serializers.rb
index 7066ebf42..66e375568 100644
--- a/lib/active_model_serializers.rb
+++ b/lib/active_model_serializers.rb
@@ -7,12 +7,22 @@
 begin
   require 'action_controller'
   require 'action_controller/serialization'
-  require 'action_controller/serialization_test_case'
 
   ActiveSupport.on_load(:action_controller) do
     if ::ActionController::Serialization.enabled
       ActionController::Base.send(:include, ::ActionController::Serialization)
-      ActionController::TestCase.send(:include, ::ActionController::SerializationAssertions)
+
+      # action_controller_test_case load hook was added in Rails 5.1
+      # https://github.com/rails/rails/commit/0510208dd1ff23baa619884c0abcae4d141fae53
+      if ActiveSupport::VERSION::STRING < '5.1'
+        require 'action_controller/serialization_test_case'
+        ActionController::TestCase.send(:include, ::ActionController::SerializationAssertions)
+      else
+        ActiveSupport.on_load(:action_controller_test_case) do
+          require 'action_controller/serialization_test_case'
+          ActionController::TestCase.send(:include, ::ActionController::SerializationAssertions)
+        end
+      end
     end
   end
 rescue LoadError