fix: handling negative grand total

(cherry picked from commit 136f92db04)

erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py

@@ -108,6 +108,14 @@ class TestSalesInvoice(ERPNextTestSuite):
 		si.save()
 		self.assertEqual(si.items[0].qty, 1)
 
+	@ERPNextTestSuite.change_settings("Selling Settings", {"allow_negative_rates_for_items": 1})
+	def test_sales_invoice_negative_grand_total_still_blocked_with_setting(self):
+		"""allow_negative_rates_for_items must not bypass the >=0 guard for a non-return
+		invoice, since invoices post to the GL (unlike Sales Order)."""
+		si = create_sales_invoice(qty=1, rate=100, do_not_save=True)
+		si.append("items", {"item_code": "_Test Item 2", "qty": 1, "rate": -150})
+		self.assertRaises(frappe.ValidationError, si.save)
+
 	def test_timestamp_change(self):
 		w = frappe.copy_doc(self.globalTestRecords["Sales Invoice"][0])
 		w.docstatus = 0

erpnext/buying/doctype/purchase_order/test_purchase_order.py

@@ -54,6 +54,19 @@ class TestPurchaseOrder(ERPNextTestSuite):
 		po.save()
 		self.assertEqual(po.items[1].qty, 1)
 
+	def test_purchase_order_negative_grand_total_blocked_by_default(self):
+		po = create_purchase_order(qty=1, rate=100, do_not_save=True)
+		po.append("items", {"item_code": "_Test Item 2", "qty": 1, "rate": -150, "schedule_date": nowdate()})
+		self.assertRaises(frappe.ValidationError, po.save)
+
+	@ERPNextTestSuite.change_settings("Buying Settings", {"allow_negative_rates_for_items": 1})
+	def test_purchase_order_negative_grand_total_allowed_with_setting(self):
+		"""A supplier change order can net to a negative grand total (credit owed)."""
+		po = create_purchase_order(qty=1, rate=100, do_not_save=True)
+		po.append("items", {"item_code": "_Test Item 2", "qty": 1, "rate": -150, "schedule_date": nowdate()})
+		po.save()
+		self.assertTrue(po.base_grand_total < 0)
+
 	def test_purchase_order_zero_qty(self):
 		po = create_purchase_order(qty=0, do_not_save=True)
 

erpnext/controllers/accounts_controller.py

@@ -241,6 +241,23 @@ class AccountsController(TransactionBase):
 				)
 				frappe.msgprint(msg)
 
+	def is_negative_grand_total_allowed(self) -> bool:
+		"""Return True if this document may save with a negative grand total.
+
+		Sales Order and Purchase Order never post to the GL, so a negative
+		total is safe there whenever the user has explicitly opted into
+		negative rates via Selling/Buying Settings. Every other
+		AccountsController doctype (invoices, delivery notes, receipts,
+		quotations, ...) keeps relying on the `is_return` escape hatch only.
+		"""
+		if self.doctype == "Sales Order":
+			return bool(frappe.get_single_value("Selling Settings", "allow_negative_rates_for_items"))
+
+		if self.doctype == "Purchase Order":
+			return bool(frappe.get_single_value("Buying Settings", "allow_negative_rates_for_items"))
+
+		return False
+
 	def validate(self):
 		if not self.get("is_return") and not self.get("is_debit_note"):
 			self.validate_qty_is_not_zero()
@@ -290,7 +307,8 @@ class AccountsController(TransactionBase):
 			self.calculate_taxes_and_totals()
 
 			if not self.meta.get_field("is_return") or not self.is_return:
-				self.validate_value("base_grand_total", ">=", 0)
+				if not self.is_negative_grand_total_allowed():
+					self.validate_value("base_grand_total", ">=", 0)
 
 			validate_return(self)
 

erpnext/controllers/status_updater.py

@@ -292,10 +292,11 @@ class StatusUpdater(Document):
 					frappe.throw(_("For an item {0}, quantity must be negative number").format(d.item_code))
 
 				if (
-					not selling_negative_rate_allowed and self.doctype in ["Sales Invoice", "Delivery Note"]
+					not selling_negative_rate_allowed
+					and self.doctype in ["Sales Order", "Sales Invoice", "Delivery Note"]
 				) or (
 					not buying_negative_rate_allowed
-					and self.doctype in ["Purchase Invoice", "Purchase Receipt"]
+					and self.doctype in ["Purchase Order", "Purchase Invoice", "Purchase Receipt"]
 				):
 					if hasattr(d, "item_code") and hasattr(d, "rate") and flt(d.rate) < 0:
 						frappe.throw(

erpnext/selling/doctype/sales_order/test_sales_order.py

@@ -157,6 +157,19 @@ class TestSalesOrder(ERPNextTestSuite):
 		)
 		update_child_qty_rate("Sales Order", trans_item, so.name)
 
+	def test_sales_order_negative_grand_total_blocked_by_default(self):
+		so = make_sales_order(qty=1, rate=100, do_not_save=True)
+		so.append("items", {"item_code": "_Test Item 2", "qty": 1, "rate": -150})
+		self.assertRaises(frappe.ValidationError, so.save)
+
+	@ERPNextTestSuite.change_settings("Selling Settings", {"allow_negative_rates_for_items": 1})
+	def test_sales_order_negative_grand_total_allowed_with_setting(self):
+		"""A subscription downgrade / change order can net to a negative grand total."""
+		so = make_sales_order(qty=1, rate=100, do_not_save=True)
+		so.append("items", {"item_code": "_Test Item 2", "qty": 1, "rate": -150})
+		so.save()
+		self.assertTrue(so.base_grand_total < 0)
+
 	@ERPNextTestSuite.change_settings("Selling Settings", {"allow_multiple_items": 1})
 	def test_sales_order_qty(self):
 		so = make_sales_order(qty=1, do_not_save=True)