Fix discarded duplicated products bug

When a product is cloned and then discarded without changing the cloned
variants SKU, if the product is ever cloned again then the cloning
process will fail with a variant and master variant SKU validation
error. This issue occurs because products and their variants are soft
deleted and therefore the copied SKU will not be unique during the
second cloning.

This commit also includes a spec to catch this error in the future.

core/lib/spree/core/product_duplicator.rb

@@ -41,8 +41,9 @@ def duplicate_product
 
     def duplicate_master
       master = product.master
+      discarded_count = Spree::Product.with_discarded.where("name like ?", "COPY OF #{product.name}").count + 1
       master.dup.tap do |new_master|
-        new_master.sku = "COPY OF #{master.sku}"
+        new_master.sku = "#{discarded_count.ordinalize} COPY OF #{new_master.sku}"
         new_master.deleted_at = nil
         new_master.images = master.images.map { |image| duplicate_image image } if @include_images
         new_master.price = master.price
@@ -51,7 +52,8 @@ def duplicate_master
 
     def duplicate_variant(variant)
       new_variant = variant.dup
-      new_variant.sku = "COPY OF #{new_variant.sku}"
+      discarded_count = Spree::Product.with_discarded.where("name like ?", "COPY OF #{product.name}").count + 1
+      new_variant.sku = "#{discarded_count.ordinalize} COPY OF #{new_variant.sku}"
       new_variant.deleted_at = nil
       new_variant.option_values = variant.option_values.map { |option_value| option_value }
       new_variant

core/spec/models/spree/product_duplicator_spec.rb

@@ -87,6 +87,11 @@ module Spree
       it "will not duplicate the option values" do
         expect{ duplicator.duplicate }.to change{ Spree::OptionValue.count }.by(0)
       end
+
+      it "will duplicate the variants after initial duplicate is discarded" do
+        duplicator.duplicate.discard
+        expect { duplicator.duplicate }.to change { Spree::Variant.count }.by(3)
+      end
     end
   end
 end

core/spec/models/spree/product_spec.rb

@@ -22,7 +22,7 @@ class Extension < Spree::Base
       it 'duplicates product' do
         clone = product.duplicate
         expect(clone.name).to eq('COPY OF ' + product.name)
-        expect(clone.master.sku).to eq('COPY OF ' + product.master.sku)
+        expect(clone.master.sku).to eq('1st COPY OF ' + product.master.sku)
         expect(clone.taxons).to eq(product.taxons)
         expect(clone.images.size).to eq(product.images.size)
       end