reverting PR #909 and adding json api usage advise on readme

test/action_controller/adapter_selector_test.rb

@@ -4,7 +4,7 @@ module ActionController
   module Serialization
     class AdapterSelectorTest < ActionController::TestCase
       class MyController < ActionController::Base
-        def render_using_the_initializer_defined_adapter
+        def render_using_default_adapter
           @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
           render json: @profile
         end
@@ -23,7 +23,7 @@ module ActionController
       tests MyController
 
       def test_render_using_default_adapter
-        get :render_using_the_initializer_defined_adapter
+        get :render_using_default_adapter
         assert_equal '{"name":"Name 1","description":"Description 1"}', response.body
       end
 

test/fixtures/poro.rb

@@ -1,5 +1,3 @@
-ActiveModel::Serializer.config.adapter = :json
-
 class Model
   def initialize(hash={})
     @attributes = hash
@@ -66,7 +64,7 @@ Author   = Class.new(Model)
 Bio      = Class.new(Model)
 Blog     = Class.new(Model)
 Role     = Class.new(Model)
-User     = Class.new(Model)
+User = Class.new(Model)
 Location = Class.new(Model)
 Place    = Class.new(Model)