fix: Add test for additional discount applied on taxes
diff --git a/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py b/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py
index 0ac816e..3a09c96 100644
--- a/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py
+++ b/erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py
@@ -268,6 +268,35 @@
 
 		check_gl_entries(self, pi.name, expected_gle, nowdate())
 
+	def test_additional_discount_for_purchase_invoice_with_discount_accounting_enabled(self):
+		from erpnext.accounts.doctype.sales_invoice.test_sales_invoice import check_gl_entries
+
+		enable_discount_accounting()
+		additional_discount_account = create_account(account_name="Discount Account",
+			parent_account="Indirect Expenses - _TC", company="_Test Company")
+		
+		pi = make_purchase_invoice(qty=1, rate=75000, do_not_save=1)
+		pi.apply_discount_on = "Grand Total"
+		pi.additional_discount_account = additional_discount_account
+		pi.additional_discount_percentage = 10
+		pi.append("taxes", {
+			"charge_type": "On Net Total",
+			"account_head": "CGST - _TC",
+			"cost_center": "Main - _TC",
+			"description": "CGST @ 9.0",
+			"rate": 9
+		})
+		pi.submit()
+
+		expected_gle = [
+			["Discount Account - _TC", 0.0, 675.0, nowdate()],
+			["CGST - _TC", 6750.0, 0.0, nowdate()],
+			["_Test Account Cost for Goods Sold - _TC", 67500.0, 0.0, nowdate()],
+			["Creditors - _TC", 0.0, 73575.0, nowdate()]
+		]
+
+		check_gl_entries(self, pi.name, expected_gle, nowdate())
+
 	def test_purchase_invoice_change_naming_series(self):
 		pi = frappe.copy_doc(test_records[1])
 		pi.insert()