Remove duplicate test helper

test/action_controller/serialization_test.rb

@@ -5,6 +5,7 @@ module Serialization
     class ImplicitSerializerTest < ActionController::TestCase
       include ActiveSupport::Testing::Stream
       class ImplicitSerializationTestController < ActionController::Base
+        include SerializationTesting
         def render_using_implicit_serializer
           @profile = Profile.new(name: 'Name 1', description: 'Description 1', comments: 'Comments 1')
           render json: @profile
@@ -123,21 +124,6 @@ def render_fragment_changed_object_with_relationship
 
           render json: like
         end
-
-        private
-
-        def generate_cached_serializer(obj)
-          ActiveModel::SerializableResource.new(obj).to_json
-        end
-
-        def with_adapter(adapter)
-          old_adapter = ActiveModel::Serializer.config.adapter
-          # JSON-API adapter sets root by default
-          ActiveModel::Serializer.config.adapter = adapter
-          yield
-        ensure
-          ActiveModel::Serializer.config.adapter = old_adapter
-        end
       end
 
       tests ImplicitSerializationTestController

test/support/serialization_testing.rb

@@ -1,13 +1,29 @@
-class Minitest::Test
-  def before_setup
-    ActionController::Base.cache_store.clear
+module SerializationTesting
+  private
+
+  def generate_cached_serializer(obj)
+    ActiveModel::SerializableResource.new(obj).to_json
   end
 
+  # Aliased as :with_configured_adapter to clarify that
+  # this method tests the configured adapter.
+  # When not testing configuration, it may be preferable
+  # to pass in the +adapter+ option to <tt>ActiveModel::SerializableResource</tt>.
+  # e.g ActiveModel::SerializableResource.new(resource, adapter: :json_api)
   def with_adapter(adapter)
     old_adapter = ActiveModel::Serializer.config.adapter
     ActiveModel::Serializer.config.adapter = adapter
     yield
   ensure
     ActiveModel::Serializer.config.adapter = old_adapter
   end
+  alias_method :with_configured_adapter, :with_adapter
+end
+
+class Minitest::Test
+  def before_setup
+    ActionController::Base.cache_store.clear
+  end
+
+  include SerializationTesting
 end