Make currency public in Spree::ReturnItem

backend/app/controllers/spree/admin/return_authorizations_controller.rb

@@ -29,7 +29,7 @@ def load_return_items
         unassociated_inventory_units = all_inventory_units - associated_inventory_units
 
         new_return_items = unassociated_inventory_units.map do |new_unit|
-          Spree::ReturnItem.new(inventory_unit: new_unit).tap(&:set_default_pre_tax_amount)
+          Spree::ReturnItem.new(inventory_unit: new_unit, return_authorization: @return_authorization).tap(&:set_default_pre_tax_amount)
         end
 
         @form_return_items = (@return_authorization.return_items + new_return_items).sort_by(&:inventory_unit_id)

core/app/models/spree/return_item.rb

@@ -163,6 +163,10 @@ def set_default_pre_tax_amount
       self.pre_tax_amount = refund_amount_calculator.new.compute(self)
     end
 
+    def currency
+      return_authorization.try(:currency) || Spree::Config[:currency]
+    end
+
     private
 
     def persist_acceptance_status_errors
@@ -176,10 +180,6 @@ def stock_item
                                stock_location_id: customer_return.stock_location_id)
     end
 
-    def currency
-      return_authorization.try(:currency) || Spree::Config[:currency]
-    end
-
     def process_inventory_unit!
       inventory_unit.return!
       if should_restock?

core/spec/models/spree/return_item_spec.rb

@@ -733,5 +733,13 @@
         it { expect { subject }.not_to change { stock_item.reload.count_on_hand } }
       end
     end
+
+    describe '#currency' do
+      subject { return_item }
+
+      it 'responds to currency method' do
+        expect { subject.respond_to?(:currency) }.to eq true
+      end
+    end
   end
 end