Reimplement Spree<2.0 :simple_product factory in OFN

spec/factories.rb

@@ -453,6 +453,10 @@ FactoryBot.define do
       Spree::Image.create(attachment: image, viewable_id: product.master.id, viewable_type: 'Spree::Variant')
     end
   end
+
+  factory :simple_product, parent: :base_product do
+    on_hand 5
+  end
 end
 
 
@@ -526,4 +530,5 @@ FactoryBot.modify do
       user.spree_roles << Spree::Role.find_or_create_by_name!('admin')
     end
   end
+
 end