Add Spree::Variant#alchemy_ingredients relation

app/decorators/models/spree/spree_variant_decorator.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+module Spree
+  module SpreeVariantDecorator
+    def self.prepended(base)
+      base.include AlchemySolidus::TouchAlchemyIngredients
+      base.has_many :alchemy_ingredients, class_name: "Alchemy::Ingredients::SpreeVariant", as: :related_object, dependent: :nullify
+    end
+
+    ::Spree::Variant.prepend self
+  end
+end

spec/models/spree/variant_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+
+RSpec.describe Spree::Variant, type: :model do
+  it { is_expected.to have_many(:alchemy_ingredients) }
+
+  describe "cache invalidation" do
+    let(:page) { create(:alchemy_page) }
+    let(:page_version) { create(:alchemy_page_version, page: page) }
+    let(:element) { create(:alchemy_element, page_version: page_version) }
+    let!(:ingredient) { Alchemy::Ingredients::SpreeVariant.create!(element: element, role: "variant", related_object: variant) }
+    let(:variant) { create(:variant) }
+
+    it "invalidates the cache on update" do
+      travel_to 5.minutes.from_now do
+        current_time = Time.current
+        expect { variant.reload.update!(price: 30) }.to change { ingredient.reload.updated_at }.to(current_time)
+        expect(element.reload.updated_at).to eq(current_time)
+        expect(page_version.reload.updated_at).to eq(current_time)
+        expect(page.reload.updated_at).to eq(current_time)
+      end
+    end
+
+    it "invalidates the cache on touch" do
+      travel_to 5.minutes.from_now do
+        current_time = Time.current
+        expect { variant.reload.touch }.to change { ingredient.reload.updated_at }.to(current_time)
+        expect(element.reload.updated_at).to eq(current_time)
+        expect(page_version.reload.updated_at).to eq(current_time)
+        expect(page.reload.updated_at).to eq(current_time)
+      end
+    end
+  end
+end