refactor: prepare for free ticket

test/models/order_test.rb

@@ -603,4 +603,22 @@ class OrderTest < ActiveSupport::TestCase
     result = order.stripe_invoice_pdf_url
     assert_nil result
   end
+
+  test "free? should return true for zero amount orders" do
+    free_order = Order.create!(
+      user: @user, event: @event, total_amount_cents: 0,
+      status: "draft", payment_attempts: 0
+    )
+
+    assert free_order.free?
+  end
+
+  test "free? should return false for non-zero amount orders" do
+    paid_order = Order.create!(
+      user: @user, event: @event, total_amount_cents: 1000,
+      status: "draft", payment_attempts: 0
+    )
+
+    assert_not paid_order.free?
+  end
 end