RFC: Json Api Errors (WIP)

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

test/serializable_resource_test.rb

@@ -31,5 +31,37 @@ module ActiveModel
     def test_use_adapter_with_adapter_option_as_false
       refute ActiveModel::SerializableResource.new(@resource, { adapter: false }).use_adapter?
     end
+
+    class SerializableResourceErrorsTest < Minitest::Test
+      def test_serializable_resource_with_errors
+        options = nil
+        resource = ModelWithErrors.new
+        resource.errors.add(:name, 'must be awesome')
+        serializable_resource = ActiveModel::SerializableResource.new(resource)
+        expected_response_document =
+          { 'errors'.freeze =>
+            [
+              { :source => { :pointer => '/data/attributes/name' }, :detail => 'must be awesome' }
+            ]
+        }
+        assert_equal serializable_resource.as_json(options), expected_response_document
+      end
+
+      def test_serializable_resource_with_collection_containing_errors
+        options = nil
+        resources = []
+        resources << resource = ModelWithErrors.new
+        resource.errors.add(:title, 'must be amazing')
+        resources << ModelWithErrors.new
+        serializable_resource = ActiveModel::SerializableResource.new(resources)
+        expected_response_document =
+          { 'errors'.freeze =>
+            [
+              { :source => { :pointer => '/data/attributes/title' }, :detail => 'must be amazing' }
+            ]
+        }
+        assert_equal serializable_resource.as_json(options), expected_response_document
+      end
+    end
   end
 end