RFC: Json Api Errors (WIP)

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

test/adapter/json_api/errors_test.rb

@@ -0,0 +1,64 @@
+require 'test_helper'
+
+module ActiveModelSerializers
+  module Adapter
+    class JsonApi < Base
+      class ErrorsTest < Minitest::Test
+        include ActiveModel::Serializer::Lint::Tests
+
+        def setup
+          @resource = ModelWithErrors.new
+        end
+
+        def test_active_model_with_error
+          options = {
+              serializer: ActiveModel::Serializer::ErrorSerializer,
+              adapter: :'json_api/error'
+          }
+
+          @resource.errors.add(:name, 'cannot be nil')
+
+          serializable_resource = ActiveModel::SerializableResource.new(@resource, options)
+          assert_equal serializable_resource.serializer_instance.attributes, {}
+          assert_equal serializable_resource.serializer_instance.object, @resource
+
+          expected_errors_object =
+            { 'errors'.freeze =>
+              [
+                {
+                  source: { pointer: '/data/attributes/name' },
+                  detail: 'cannot be nil'
+                }
+              ]
+          }
+          assert_equal serializable_resource.as_json, expected_errors_object
+        end
+
+        def test_active_model_with_multiple_errors
+          options = {
+              serializer: ActiveModel::Serializer::ErrorSerializer,
+              adapter: :'json_api/error'
+          }
+
+          @resource.errors.add(:name, 'cannot be nil')
+          @resource.errors.add(:name, 'must be longer')
+          @resource.errors.add(:id, 'must be a uuid')
+
+          serializable_resource = ActiveModel::SerializableResource.new(@resource, options)
+          assert_equal serializable_resource.serializer_instance.attributes, {}
+          assert_equal serializable_resource.serializer_instance.object, @resource
+
+          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' }
+              ]
+          }
+          assert_equal serializable_resource.as_json, expected_errors_object
+        end
+      end
+    end
+  end
+end