Only load test helpers in the test environment

lib/active_model/serializer/railtie.rb

@@ -20,6 +20,8 @@ class Railtie < Rails::Railtie
       require 'generators/serializer/resource_override'
     end
 
-    ActionController::TestCase.send(:include, ActiveModelSerializers::Test::Serializer)
+    if Rails.env.test?
+      ActionController::TestCase.send(:include, ActiveModelSerializers::Test::Serializer)
+    end
   end
 end

lib/active_model_serializers.rb

@@ -13,6 +13,7 @@ def self.config
   autoload :Model
   autoload :Callbacks
   autoload :Logging
+  autoload :Test
 
   module_function
 
@@ -51,7 +52,6 @@ def silence_warnings
 require 'active_model/serializer'
 require 'active_model/serializable_resource'
 require 'active_model/serializer/version'
-require 'active_model_serializers/test/serializer'
 
 require 'action_controller/serialization'
 ActiveSupport.on_load(:action_controller) do

lib/active_model_serializers/test.rb

@@ -0,0 +1,5 @@
+module ActiveModelSerializers
+  module Test
+    autoload :Serializer, 'active_model_serializers/test/serializer'
+  end
+end

test/active_model_serializers/test/serializer_test.rb

@@ -4,6 +4,8 @@
 module ActiveModelSerializers
   module Test
     class SerializerTest < ActionController::TestCase
+      include ActiveModelSerializers::Test::Serializer
+
       class MyController < ActionController::Base
         def render_using_serializer
           render json: Profile.new(name: 'Name 1', description: 'Description 1', comments: 'Comments 1')