fix: don't allow negative rate (backport #36027) (#36465)

* fix: don't allow negative rates (#36027)

* fix: don't allow negative rate

* test: don't allow negative rate

* fix: only check for -rate on items child table

(cherry picked from commit dedf24b86d)

# Conflicts:
#	erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py

* chore: resolve merge conflict

---------

Co-authored-by: Devin Slauenwhite <devin.slauenwhite@gmail.com>
Co-authored-by: ruthra kumar <ruthra@erpnext.com>

erpnext/accounts/doctype/sales_invoice/test_sales_invoice.py

@@ -3316,6 +3316,13 @@ class TestSalesInvoice(unittest.TestCase):
 		)
 		self.assertRaises(frappe.ValidationError, si.submit)
 
+	def test_sales_return_negative_rate(self):
+		si = create_sales_invoice(is_return=1, qty=-2, rate=-10, do_not_save=True)
+		self.assertRaises(frappe.ValidationError, si.save)
+
+		si.items[0].rate = 10
+		si.save()
+
 
 def get_sales_invoice_for_e_invoice():
 	si = make_sales_invoice_for_ewaybill()

erpnext/controllers/status_updater.py

@@ -233,6 +233,9 @@ class StatusUpdater(Document):
 				if hasattr(d, "qty") and d.qty > 0 and self.get("is_return"):
 					frappe.throw(_("For an item {0}, quantity must be negative number").format(d.item_code))
 
+				if hasattr(d, "item_code") and hasattr(d, "rate") and d.rate < 0:
+					frappe.throw(_("For an item {0}, rate must be a positive number").format(d.item_code))
+
 				if d.doctype == args["source_dt"] and d.get(args["join_field"]):
 					args["name"] = d.get(args["join_field"])