Add dependent: :destroy to Spree::Order#order_promotions

core/app/models/spree/order.rb

@@ -104,7 +104,7 @@ def states
              foreign_key: :order_id,
              dependent: :destroy,
              inverse_of: :order
-    has_many :order_promotions, class_name: 'Spree::OrderPromotion'
+    has_many :order_promotions, class_name: 'Spree::OrderPromotion', dependent: :destroy
     has_many :promotions, through: :order_promotions
 
     # Payments

core/db/migrate/20231027084517_add_order_promotions_foreign_key.rb

@@ -0,0 +1,10 @@
+class AddOrderPromotionsForeignKey < ActiveRecord::Migration[7.0]
+  def up
+    Spree::OrderPromotion.left_joins(:order).where(spree_orders: { id: nil }).delete_all
+    add_foreign_key :spree_orders_promotions, :spree_orders, column: :order_id, validate: false, on_delete: :cascade
+  end
+
+  def down
+    remove_foreign_key :spree_orders_promotions, :spree_orders
+  end
+end

core/spec/models/spree/order_spec.rb

@@ -1818,4 +1818,18 @@ def validate(line_item)
       end
     end
   end
+
+  describe "order deletion" do
+    let(:order) { create(:order) }
+    let(:promotion) { create(:promotion) }
+
+    subject { order.destroy }
+    before do
+      order.promotions << promotion
+    end
+
+    it "deletes join table entries when deleting an order" do
+      expect { subject }.to change { Spree::OrderPromotion.count }.from(1).to(0)
+    end
+  end
 end