RFC: Json Api Errors (WIP)

- ActiveModelSerializers::JsonPointer
- ActiveModel::Serializer::Adapter::JsonApi::Error
- ActiveModel::Serializer::Adapter::JsonApi::Error.attributes
- Fix rubocop config

test/action_controller/json_api/errors_test.rb

@@ -0,0 +1,41 @@
+require 'test_helper'
+
+module ActionController
+  module Serialization
+    class JsonApi
+      class ErrorsTest < ActionController::TestCase
+        def test_active_model_with_multiple_errors
+          get :render_resource_with_errors
+
+          expected_errors_object =
+            { 'errors'.freeze =>
+              [
+                { :source => { :pointer => '/data/attributes/name' }, :detail => 'cannot be nil' },
+                { :source => { :pointer => '/data/attributes/name' }, :detail => 'must be longer' },
+                { :source => { :pointer => '/data/attributes/id' }, :detail => 'must be a uuid' }
+              ]
+          }.to_json
+          assert_equal json_reponse_body.to_json, expected_errors_object
+        end
+
+        def json_reponse_body
+          JSON.load(@response.body)
+        end
+
+        class ErrorsTestController < ActionController::Base
+          def render_resource_with_errors
+            resource = Profile.new(name: 'Name 1',
+                                   description: 'Description 1',
+                                   comments: 'Comments 1')
+            resource.errors.add(:name, 'cannot be nil')
+            resource.errors.add(:name, 'must be longer')
+            resource.errors.add(:id, 'must be a uuid')
+            render json: resource, adapter: :json_api
+          end
+        end
+
+        tests ErrorsTestController
+      end
+    end
+  end
+end