diff --git a/erpnext/selling/doctype/sales_order/test_sales_order.py b/erpnext/selling/doctype/sales_order/test_sales_order.py
index c85a4fb..954393f 100644
--- a/erpnext/selling/doctype/sales_order/test_sales_order.py
+++ b/erpnext/selling/doctype/sales_order/test_sales_order.py
@@ -2055,7 +2055,7 @@
 	so.company = args.company or "_Test Company"
 	so.customer = args.customer or "_Test Customer"
 	so.currency = args.currency or "INR"
-	so.po_no = args.po_no or "12345"
+	so.po_no = args.po_no or ""
 	if args.selling_price_list:
 		so.selling_price_list = args.selling_price_list
 
diff --git a/erpnext/stock/doctype/delivery_note/test_delivery_note.py b/erpnext/stock/doctype/delivery_note/test_delivery_note.py
index 0ef3027..48b8ab7 100644
--- a/erpnext/stock/doctype/delivery_note/test_delivery_note.py
+++ b/erpnext/stock/doctype/delivery_note/test_delivery_note.py
@@ -703,7 +703,7 @@
 
 	def test_dn_billing_status_case1(self):
 		# SO -> DN -> SI
-		so = make_sales_order()
+		so = make_sales_order(po_no="12345")
 		dn = create_dn_against_so(so.name, delivered_qty=2)
 
 		self.assertEqual(dn.status, "To Bill")
@@ -730,7 +730,7 @@
 			make_sales_invoice,
 		)
 
-		so = make_sales_order()
+		so = make_sales_order(po_no="12345")
 
 		si = make_sales_invoice(so.name)
 		si.get("items")[0].qty = 5
@@ -774,7 +774,7 @@
 
 		frappe.db.set_single_value("Stock Settings", "allow_negative_stock", 1)
 
-		so = make_sales_order()
+		so = make_sales_order(po_no="12345")
 
 		dn1 = make_delivery_note(so.name)
 		dn1.get("items")[0].qty = 2
@@ -820,7 +820,7 @@
 		from erpnext.accounts.doctype.sales_invoice.sales_invoice import make_delivery_note
 		from erpnext.selling.doctype.sales_order.sales_order import make_sales_invoice
 
-		so = make_sales_order()
+		so = make_sales_order(po_no="12345")
 
 		si = make_sales_invoice(so.name)
 		si.submit()
@@ -1227,6 +1227,7 @@
 		self.assertEqual(get_reserved_qty(item, warehouse), 0 if dont_reserve_qty else qty_to_reserve)
 
 	def tearDown(self):
+		frappe.db.rollback()
 		frappe.db.set_single_value("Selling Settings", "dont_reserve_sales_order_qty_on_sales_return", 0)