Improve nil-safety in variant naming methods

app/services/variant_units/variant_and_line_item_naming.rb

@@ -22,7 +22,8 @@ module VariantUnits
     end
 
     def product_and_full_name
-      return "#{product.name} - #{full_name}" unless full_name.start_with? product.name
+      return product.name if full_name.blank?
+      return "#{product.name} - #{full_name}" unless full_name.start_with?(product.name)
 
       full_name
     end
@@ -51,7 +52,7 @@ module VariantUnits
       return display_as if has_attribute?(:display_as) && display_as.present?
       return variant.display_as if variant_display_as?
 
-      options_text
+      options_text.to_s
     end
 
     def assign_units

spec/models/spree/variant_spec.rb

@@ -432,6 +432,20 @@ describe Spree::Variant do
         expect(variant.product_and_full_name).to eq "Apple - Pink Lady"
       end
     end
+
+    context "when related naming values are nil" do
+      before do
+        product.name = "Apples"
+        product.display_as = nil
+        variant.display_as = nil
+        variant.unit_presentation = nil
+      end
+
+      it "returns empty string or product name" do
+        expect(variant.full_name).to eq ""
+        expect(variant.product_and_full_name).to eq product.name
+      end
+    end
   end
 
   describe "calculating the price with enterprise fees" do