fix: validate duplicate serial no on submit in DN (#37243)

erpnext/stock/doctype/delivery_note/delivery_note.py

@@ -138,7 +138,9 @@ class DeliveryNote(SellingController):
 		self.validate_uom_is_integer("stock_uom", "stock_qty")
 		self.validate_uom_is_integer("uom", "qty")
 		self.validate_with_previous_doc()
-		self.validate_duplicate_serial_nos()
+
+		if self.get("_action") == "submit":
+			self.validate_duplicate_serial_nos()
 
 		from erpnext.stock.doctype.packed_item.packed_item import make_packing_list
 

erpnext/stock/doctype/delivery_note/test_delivery_note.py

@@ -1234,14 +1234,10 @@ class TestDeliveryNote(FrappeTestCase):
 		)
 		dn.items[0].serial_no = "\n".join(serial_nos[:2])
 		dn.append("items", dn.items[0].as_dict())
+		dn.save()
 
 		# Test - 1: ValidationError should be raised
-		self.assertRaises(frappe.ValidationError, dn.save)
-
-		# Step - 4: Submit Delivery Note with unique Serial Nos
-		dn.items[1].serial_no = "\n".join(serial_nos[2:])
-		dn.save()
-		dn.submit()
+		self.assertRaises(frappe.ValidationError, dn.submit)
 
 	def tearDown(self):
 		frappe.db.rollback()