Change line_item_syncer to verify stock if order is already complete, this will happen for orders in the current OC when a subscription is changed

app/services/line_item_syncer.rb

@@ -30,7 +30,7 @@ class LineItemSyncer
 
   def create_new_items(order)
     new_subscription_line_items.each do |sli|
-      order.line_items.create(variant_id: sli.variant_id, quantity: sli.quantity, skip_stock_check: true)
+      order.line_items.create(variant_id: sli.variant_id, quantity: sli.quantity, skip_stock_check: skip_stock_check?(order))
     end
   end
 
@@ -48,8 +48,12 @@ class LineItemSyncer
 
   def update_quantity(line_item, sli)
     if line_item.quantity == sli.quantity_was
-      return line_item.update_attributes(quantity: sli.quantity, skip_stock_check: true)
+      return line_item.update_attributes(quantity: sli.quantity, skip_stock_check: skip_stock_check?(line_item.order))
     end
     line_item.quantity == sli.quantity
   end
+
+  def skip_stock_check?(order)
+    !order.complete?
+  end
 end

spec/services/order_syncer_spec.rb

@@ -391,13 +391,31 @@ describe OrderSyncer do
       let(:params) { { subscription_line_items_attributes: [{ id: sli.id, quantity: 3 }] } }
       let(:syncer) { OrderSyncer.new(subscription) }
 
-      it "updates the line_item quantities and totals on all orders" do
+      before do
         expect(order.reload.total.to_f).to eq 59.97
         subscription.assign_attributes(params)
-        expect(syncer.sync!).to be true
-        line_items = Spree::LineItem.where(order_id: subscription.orders, variant_id: sli.variant_id)
-        expect(line_items.map(&:quantity)).to eq [3]
-        expect(order.reload.total.to_f).to eq 99.95
+      end
+
+      context "when order is not complete" do
+        it "updates the line_item quantities and totals on all orders" do
+          expect(syncer.sync!).to be true
+
+          line_items = Spree::LineItem.where(order_id: subscription.orders, variant_id: sli.variant_id)
+          expect(line_items.map(&:quantity)).to eq [3]
+          expect(order.reload.total.to_f).to eq 99.95
+        end
+      end
+
+      context "when order is complete" do
+        before { AdvanceOrderService.new(order).call }
+
+        it "does not update the line_item quantities and totals on all orders" do
+          expect(syncer.sync!).to be true
+
+          line_items = Spree::LineItem.where(order_id: subscription.orders, variant_id: sli.variant_id)
+          expect(line_items.map(&:quantity)).to eq [1]
+          expect(order.reload.total.to_f).to eq 59.97
+        end
       end
     end