Move caching initialization to Railtie

Also
- Add reference to config from ActiveModelSerializers.config
- correctly call super in FragmentCacheTest#setup
- rename test rails app from Foo to ActiveModelSerializers::RailsApplication

lib/active_model/serializer.rb

@@ -152,7 +152,7 @@ module ActiveModel
     # @todo require less code comments. See
     # https://github.com/rails-api/active_model_serializers/pull/1249#issuecomment-146567837
     def self.cache(options = {})
-      self._cache = ActionController::Base.cache_store if Rails.configuration.action_controller.perform_caching
+      self._cache = ActiveModelSerializers.config.cache_store if ActiveModelSerializers.config.perform_caching
       self._cache_key = options.delete(:key)
       self._cache_only = options.delete(:only)
       self._cache_except = options.delete(:except)

lib/active_model/serializer/railtie.rb

@@ -8,6 +8,13 @@ module ActiveModel
       end
     end
 
+    initializer 'active_model_serializers.caching' do
+      ActiveSupport.on_load(:action_controller) do
+        ActiveModelSerializers.config.cache_store     = ActionController::Base.cache_store
+        ActiveModelSerializers.config.perform_caching = Rails.configuration.action_controller.perform_caching
+      end
+    end
+
     initializer 'generators' do |app|
       app.load_generators
       require 'generators/serializer/resource_override'

lib/active_model_serializers.rb

@@ -5,6 +5,10 @@ require 'action_controller/railtie'
 module ActiveModelSerializers
   mattr_accessor(:logger) { ActiveSupport::TaggedLogging.new(ActiveSupport::Logger.new(STDOUT)) }
 
+  def self.config
+    ActiveModel::Serializer.config
+  end
+
   extend ActiveSupport::Autoload
   autoload :Model
   autoload :Callbacks

test/adapter/fragment_cache_test.rb

@@ -4,6 +4,7 @@ module ActiveModel
     module Adapter
       class FragmentCacheTest < Minitest::Test
         def setup
+          super
           @spam            = Spam::UnrelatedLink.new(id: 'spam-id-1')
           @author          = Author.new(name: 'Joao M. D. Moura')
           @role            = Role.new(name: 'Great Author', description: nil)

test/support/rails_app.rb

@@ -1,14 +1,18 @@
-class Foo < Rails::Application
+class ActiveModelSerializers::RailsApplication < Rails::Application
   if Rails::VERSION::MAJOR >= 4
     config.eager_load = false
+
     config.secret_key_base = 'abc123'
-    config.action_controller.perform_caching = true
+
     config.active_support.test_order = :random
+
     config.logger = Logger.new(nil)
+
+    config.action_controller.perform_caching = true
     ActionController::Base.cache_store = :memory_store
   end
 end
-Foo.initialize!
+ActiveModelSerializers::RailsApplication.initialize!
 
 module TestHelper
   Routes = ActionDispatch::Routing::RouteSet.new