Add tests around unit price in backoffice

3 cases:
 - creating a new product
 - creating a new variant
 - editing an existing variant

spec/features/admin/unit_price_spec.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+feature '
+    As an admin
+    I want to check the unit price of my products/variants
+' do
+  include AuthenticationHelper
+  include WebHelper
+  
+  let!(:stock_location) { create(:stock_location, backorderable_default: false) }
+  
+  before do
+    allow(OpenFoodNetwork::FeatureToggle).to receive(:enabled?).with(:unit_price, anything) { true }
+  end
+  
+  describe "product", js: true do
+    scenario "creating a new product" do
+      login_as_admin_and_visit spree.admin_products_path
+      click_link 'New Product'
+      select "Weight (kg)", from: 'product_variant_unit_with_scale'
+      fill_in 'Value', with: '1'
+      fill_in 'Price', with: '1'
+      
+      expect(find_field("Unit Price", disabled: true).value).to eq "$1.00 / kg"
+    end
+  end
+
+  describe "variant", js: true do
+    scenario "creating a new variant" do
+      product = create(:simple_product, variant_unit: "weight", variant_unit_scale: "1")
+      login_as_admin_and_visit spree.admin_product_variants_path product
+      click_link 'New Variant'
+      fill_in 'Weight (g)', with: '1'
+      fill_in 'Price', with: '1'
+      
+      expect(find_field("Unit Price", disabled: true).value).to eq '$1,000.00 / kg'
+    end
+
+    scenario "editing a variant" do
+      product = create(:simple_product, variant_unit: "weight", variant_unit_scale: "1")
+      variant = product.variants.first
+      variant.update(price: 1.0)
+      login_as_admin_and_visit spree.edit_admin_product_variant_path(product, variant)
+      
+      expect(find_field("Unit Price", disabled: true).value).to eq '$1,000.00 / kg'
+    end
+  end
+end