Add missing object context needed for tests to be run alone

Author: bf4

test/action_controller/serialization_test.rb

@@ -454,7 +454,7 @@ def use_adapter?
       end
 
       def test_render_event_is_emmited
-        ActiveSupport::Notifications.subscribe('render.active_model_serializers') do |name|
+        ::ActiveSupport::Notifications.subscribe('render.active_model_serializers') do |name|
           @name = name
         end
 

test/active_model_serializers/adapter_for_test.rb

@@ -1,5 +1,7 @@
+require 'test_helper'
+
 module ActiveModelSerializers
-  class AdapterForTest < ActiveSupport::TestCase
+  class AdapterForTest < ::ActiveSupport::TestCase
     UnknownAdapterError = ::ActiveModelSerializers::Adapter::UnknownAdapterError
 
     def test_serializer_adapter_returns_configured_adapter