fix: reject Bank Guarantee whose end date precedes its start date

erpnext/accounts/doctype/bank_guarantee/bank_guarantee.py

@@ -5,6 +5,7 @@
 import frappe
 from frappe import _
 from frappe.model.document import Document
+from frappe.utils import getdate
 
 
 class BankGuarantee(Document):
@@ -46,6 +47,9 @@ class BankGuarantee(Document):
 		if not (self.customer or self.supplier):
 			frappe.throw(_("Select the customer or supplier."))
 
+		if self.end_date and getdate(self.end_date) < getdate(self.start_date):
+			frappe.throw(_("End Date cannot be before Start Date."))
+
 	def on_submit(self):
 		if not self.bank_guarantee_number:
 			frappe.throw(_("Enter the Bank Guarantee Number before submitting."))

erpnext/accounts/doctype/bank_guarantee/test_bank_guarantee.py

@@ -67,10 +67,6 @@ class TestBankGuarantee(ERPNextTestSuite):
 		self.assertEqual(details.customer, so.customer)
 		self.assertEqual(flt(details.grand_total), flt(so.grand_total))
 
-	def test_end_date_before_start_date_is_not_validated(self):
-		# SUSPECTED BUG: validate() never checks that end_date >= start_date, so a
-		# guarantee that expires before it starts saves cleanly. Locking the current
-		# (wrong) behaviour so a future fix that adds the check trips this test.
+	def test_end_date_before_start_date_is_rejected(self):
 		doc = self.make_bg(start_date="2026-06-30", end_date="2026-06-01")
-		doc.insert()
-		self.assertTrue(frappe.db.exists("Bank Guarantee", doc.name))
+		self.assertRaises(frappe.ValidationError, doc.insert)