add specs

spec/factories/multi_order.rb

@@ -0,0 +1,21 @@
+require 'factory_bot'
+
+FactoryBot.define do
+  factory :multi_order do
+    transient do
+      orders { [create(:order, state: 'closed')] }
+    end
+
+    after(:build) do |multi_order, evaluator|
+      # Assign orders before validation so custom validations can see them
+      multi_order.orders = evaluator.orders
+    end
+
+    after(:create) do |multi_order, _evaluator|
+      # Persist the relationship by updating the orders (if needed)
+      multi_order.orders.each do |order|
+        order.update!(multi_order: multi_order)
+      end
+    end
+  end
+end