test: add coverage for Warehouse Wise Stock Balance report

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

erpnext/stock/report/warehouse_wise_stock_balance/test_warehouse_wise_stock_balance.py

@@ -0,0 +1,31 @@
+# Copyright (c) 2026, Frappe Technologies Pvt. Ltd. and Contributors
+# See license.txt
+
+import frappe
+
+from erpnext.stock.doctype.item.test_item import make_item
+from erpnext.stock.doctype.stock_entry.stock_entry_utils import make_stock_entry
+from erpnext.stock.doctype.warehouse.test_warehouse import create_warehouse
+from erpnext.stock.report.warehouse_wise_stock_balance.warehouse_wise_stock_balance import execute
+from erpnext.tests.utils import ERPNextTestSuite
+
+
+class TestWarehouseWiseStockBalance(ERPNextTestSuite):
+	def run_report(self, **extra):
+		filters = frappe._dict({"company": "_Test Company", **extra})
+		return execute(filters)[1]
+
+	def row(self, data, warehouse):
+		return next(w for w in data if w["name"] == warehouse)
+
+	def test_balance_and_parent_accumulation(self):
+		parent = create_warehouse("_Test WWSB Parent", properties={"is_group": 1})
+		child = create_warehouse("_Test WWSB Child", properties={"parent_warehouse": parent})
+
+		make_stock_entry(item_code=make_item().name, to_warehouse=child, qty=10, rate=100)
+
+		data = self.run_report()
+		# stock balance = sum of stock value difference (10 * 100)
+		self.assertEqual(self.row(data, child)["stock_balance"], 1000)
+		# the group warehouse rolls up its children
+		self.assertEqual(self.row(data, parent)["stock_balance"], 1000)