12570 - fix variant's display_as field being empty issue

- New variant unit_value is empty, so +VariantUnits::OptionValueNamer.new(variant).name+ returns ""
- Now we are making sure that new variant unit_value won't be empty

app/helpers/admin/products_helper.rb

@@ -9,5 +9,23 @@ module Admin
         new_admin_product_image_path(product.id)
       end
     end
+
+    def prepare_new_variant(product)
+      product.variants.build do |variant|
+        variant.unit_value = 1.0 * product.variant_unit_scale
+        variant.unit_presentation = VariantUnits::OptionValueNamer.new(variant).name
+      end
+    end
+
+    def unit_value_with_description(variant)
+      scaled_unit_value = variant.unit_value / (variant.product.variant_unit_scale || 1)
+      precised_unit_value = number_with_precision(
+        scaled_unit_value,
+        precision: nil,
+        strip_insignificant_zeros: true
+      )
+
+      [precised_unit_value, variant.unit_description].compact_blank.join(" ")
+    end
   end
 end

app/views/admin/products_v3/_product_variant_row.html.haml

@@ -11,7 +11,7 @@
         %tr.condensed{ id: dom_id(variant), 'data-controller': "variant", 'class': "nested-form-wrapper", 'data-new-record': variant.new_record? ? "true" : false }
           = render partial: 'variant_row', locals: { variant:, f: variant_form, category_options:, tax_category_options:, producer_options: }
 
-    = form.fields_for("products][#{product_index}][variants_attributes][NEW_RECORD", product.variants.build) do |new_variant_form|
+    = form.fields_for("products][#{product_index}][variants_attributes][NEW_RECORD", prepare_new_variant(product)) do |new_variant_form|
       %template{ 'data-nested-form-target': "template" }
         %tr.condensed{ 'data-controller': "variant", 'class': "nested-form-wrapper", 'data-new-record': "true" }
           = render partial: 'variant_row', locals: { variant: new_variant_form.object, f: new_variant_form, category_options:, tax_category_options:, producer_options: }

app/views/admin/products_v3/_variant_row.html.haml

@@ -17,10 +17,8 @@
       -# Show a composite field for unit_value and unit_description
       = f.hidden_field :unit_value
       = f.hidden_field :unit_description
-      -# todo: create a method for value_with_description
       = f.text_field :unit_value_with_description,
-          value: [number_with_precision((variant.unit_value || 1) / (variant.product.variant_unit_scale || 1), precision: nil, strip_insignificant_zeros: true), variant.unit_description].compact_blank.join(" "),
-          'aria-label': t('admin.products_page.columns.unit_value'), required: true
+          value: unit_value_with_description(variant), 'aria-label': t('admin.products_page.columns.unit_value'), required: true
     .field
       = f.label :display_as, t('admin.products_page.columns.display_as')
       = f.text_field :display_as, placeholder: VariantUnits::OptionValueNamer.new(variant).name

spec/system/admin/products_v3/update_spec.rb

@@ -517,7 +517,6 @@ RSpec.describe 'As an enterprise user, I can update my products', feature: :admi
             expect(page).to have_field "SKU", with: "n" * 256
             expect(page).to have_content "is too long"
             expect(page.find_button("Unit")).to have_text "" # have_button selector don't work here
-            expect(page).to have_content "can't be blank"
             expect(page).to have_field "Price", with: "10.25" # other updated value is retained
           end