fix(invoice):validate return invoice qty (backport #46451) (#46481)

fix(invoice):validate return invoice qty (#46451)

* fix(invoice): validate return quantity when update stock is unchecked

* test: add unit test for validating fully returned invoice quantity

(cherry picked from commit ba96c86576)

Co-authored-by: Bhavansathru <122002510+Bhavan23@users.noreply.github.com>

erpnext/accounts/doctype/purchase_invoice/test_purchase_invoice.py

@@ -2669,6 +2669,20 @@ class TestPurchaseInvoice(FrappeTestCase, StockTestMixin):
 		)
 		self.assertEqual(actual, expected)
 
+	def test_prevents_fully_returned_invoice_with_zero_quantity(self):
+		from erpnext.controllers.sales_and_purchase_return import StockOverReturnError, make_return_doc
+
+		invoice = make_purchase_invoice(qty=10)
+
+		return_doc = make_return_doc(invoice.doctype, invoice.name)
+		return_doc.items[0].qty = -10
+		return_doc.save().submit()
+
+		return_doc = make_return_doc(invoice.doctype, invoice.name)
+		return_doc.items[0].qty = 0
+
+		self.assertRaises(StockOverReturnError, return_doc.save)
+
 
 def set_advance_flag(company, flag, default_account):
 	frappe.db.set_value(

erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py

@@ -4295,6 +4295,20 @@ class TestSalesInvoice(FrappeTestCase):
 		pos_return = make_sales_return(pos.name)
 		self.assertEqual(abs(pos_return.payments[0].amount), pos.payments[0].amount)
 
+	def test_prevents_fully_returned_invoice_with_zero_quantity(self):
+		from erpnext.controllers.sales_and_purchase_return import StockOverReturnError, make_return_doc
+
+		invoice = create_sales_invoice(qty=10)
+
+		return_doc = make_return_doc(invoice.doctype, invoice.name)
+		return_doc.items[0].qty = -10
+		return_doc.save().submit()
+
+		return_doc = make_return_doc(invoice.doctype, invoice.name)
+		return_doc.items[0].qty = 0
+
+		self.assertRaises(StockOverReturnError, return_doc.save)
+
 
 def set_advance_flag(company, flag, default_account):
 	frappe.db.set_value(

erpnext/controllers/sales_and_purchase_return.py

@@ -25,9 +25,6 @@ def validate_return(doc):
 	if doc.return_against:
 		validate_return_against(doc)
 
-		if doc.doctype in ("Sales Invoice", "Purchase Invoice") and not doc.update_stock:
-			return
-
 		validate_returned_items(doc)
 
 
@@ -118,7 +115,7 @@ def validate_returned_items(doc):
 		elif doc.doctype == "Delivery Note":
 			key = (d.item_code, d.get("dn_detail"))
 
-		if d.item_code and (flt(d.qty) < 0 or flt(d.get("received_qty")) < 0):
+		if d.item_code and (flt(d.qty) <= 0 or flt(d.get("received_qty")) <= 0):
 			if key not in valid_items:
 				frappe.msgprint(
 					_("Row # {0}: Returned Item {1} does not exist in {2} {3}").format(
@@ -160,6 +157,9 @@ def validate_returned_items(doc):
 
 def validate_quantity(doc, key, args, ref, valid_items, already_returned_items):
 	fields = ["stock_qty"]
+	if (doc.doctype == "Purchase Invoice" or doc.doctype == "Sales Invoice") and not doc.update_stock:
+		fields = ["qty"]
+
 	if doc.doctype in ["Purchase Receipt", "Purchase Invoice", "Subcontracting Receipt"]:
 		if not args.get("return_qty_from_rejected_warehouse"):
 			fields.extend(["received_qty", "rejected_qty"])
@@ -169,13 +169,16 @@ def validate_quantity(doc, key, args, ref, valid_items, already_returned_items):
 	already_returned_data = already_returned_items.get(key) or {}
 
 	company_currency = erpnext.get_company_currency(doc.company)
-	stock_qty_precision = get_field_precision(
-		frappe.get_meta(doc.doctype + " Item").get_field("stock_qty"), company_currency
+	field_precision = get_field_precision(
+		frappe.get_meta(doc.doctype + " Item").get_field(
+			"stock_qty" if doc.get("update_stock", "") else "qty"
+		),
+		company_currency,
 	)
 
 	for column in fields:
 		returned_qty = (
-			flt(already_returned_data.get(column, 0), stock_qty_precision)
+			flt(already_returned_data.get(column, 0), field_precision)
 			if len(already_returned_data) > 0
 			else 0
 		)
@@ -190,17 +193,17 @@ def validate_quantity(doc, key, args, ref, valid_items, already_returned_items):
 			reference_qty = ref.get(column) * ref.get("conversion_factor", 1.0)
 			current_stock_qty = args.get(column) * args.get("conversion_factor", 1.0)
 
-		max_returnable_qty = flt(flt(reference_qty, stock_qty_precision) - returned_qty, stock_qty_precision)
+		max_returnable_qty = flt(flt(reference_qty, field_precision) - returned_qty, field_precision)
 		label = column.replace("_", " ").title()
 
 		if reference_qty:
 			if flt(args.get(column)) > 0:
 				frappe.throw(_("{0} must be negative in return document").format(label))
-			elif returned_qty >= reference_qty and args.get(column):
+			elif returned_qty >= reference_qty and args.get(column) >= 0:
 				frappe.throw(
 					_("Item {0} has already been returned").format(args.item_code), StockOverReturnError
 				)
-			elif abs(flt(current_stock_qty, stock_qty_precision)) > max_returnable_qty:
+			elif abs(flt(current_stock_qty, field_precision)) > max_returnable_qty:
 				frappe.throw(
 					_("Row # {0}: Cannot return more than {1} for Item {2}").format(
 						args.idx, max_returnable_qty, args.item_code