Use existing product factory, the custom product is not needed here

spec/models/spree/asset_spec.rb

@@ -5,7 +5,7 @@ require 'spec_helper'
 describe Spree::Asset do
   describe "#viewable" do
     it "touches association" do
-      product = create(:custom_product)
+      product = create(:product)
       asset = Spree::Asset.create! { |a| a.viewable = product.master }
 
       product.update_column(:updated_at, 1.day.ago)