test(stock): cover multi select item and warehouse filters in warehouse wise item balance

three cases: multiple warehouses get a column each plus the total qty
column, a selected group warehouse still expands to its children, and
multiple items report side by side while unselected items stay out.

erpnext/stock/report/warehouse_wise_item_balance_age_and_value/test_warehouse_wise_item_balance_age_and_value.py

@@ -3,7 +3,9 @@
 
 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_item_balance_age_and_value.warehouse_wise_item_balance_age_and_value import (
 	execute,
 )
@@ -23,6 +25,17 @@ class TestWarehouseWiseItemBalanceAgeAndValue(ERPNextTestSuite):
 		filters.update(extra)
 		return execute(filters)[1]
 
+	def run_report_with_columns(self, **extra):
+		filters = frappe._dict(
+			{
+				"company": "_Test Company",
+				"from_date": "2026-01-01",
+				"to_date": "2026-12-31",
+			}
+		)
+		filters.update(extra)
+		return execute(filters)
+
 	def test_balance_qty_and_value(self):
 		item_code = "_Test Item"
 		warehouse = "Stores - _TC"
@@ -53,3 +66,58 @@ class TestWarehouseWiseItemBalanceAgeAndValue(ERPNextTestSuite):
 		self.assertEqual(row[6], 6)
 		# index 4 -> total stock value (6 units @ 100)
 		self.assertEqual(row[4], 600)
+
+	def test_multiple_warehouse_filter(self):
+		item_code = make_item(properties={"is_stock_item": 1}).name
+		wh_a = create_warehouse("_Test Multi Balance WH A")
+		wh_b = create_warehouse("_Test Multi Balance WH B")
+
+		make_stock_entry(item_code=item_code, to_warehouse=wh_a, qty=10, rate=100, posting_date="2026-06-01")
+		make_stock_entry(item_code=item_code, to_warehouse=wh_b, qty=25, rate=100, posting_date="2026-06-01")
+
+		columns, data = self.run_report_with_columns(item_code=item_code, warehouse=[wh_a, wh_b])
+
+		# a column per selected warehouse, preceded by the total qty column
+		self.assertEqual(columns[-3:], ["Total Qty:Int:120", f"{wh_a}:Int:100", f"{wh_b}:Int:100"])
+
+		rows = [row for row in data if row[0] == item_code]
+		self.assertEqual(len(rows), 1)
+
+		# [item, item_name, item_group, brand, value, age, total_qty, qty_wh_a, qty_wh_b]
+		row = rows[0]
+		self.assertEqual(row[4], 3500)
+		self.assertEqual(row[-3:], [35, 10, 25])
+
+	def test_group_warehouse_filter_expands_to_children(self):
+		item_code = make_item(properties={"is_stock_item": 1}).name
+		wh_a = create_warehouse("_Test Multi Balance WH A")
+
+		make_stock_entry(item_code=item_code, to_warehouse=wh_a, qty=10, rate=100, posting_date="2026-06-01")
+
+		columns, data = self.run_report_with_columns(
+			item_code=item_code, warehouse=["_Test Warehouse Group - _TC"]
+		)
+
+		self.assertIn(f"{wh_a}:Int:100", columns)
+
+		rows = [row for row in data if row[0] == item_code]
+		self.assertEqual(len(rows), 1)
+		self.assertEqual(rows[0][columns.index(f"{wh_a}:Int:100")], 10)
+
+	def test_multiple_item_filter(self):
+		item_a = make_item(properties={"is_stock_item": 1}).name
+		item_b = make_item(properties={"is_stock_item": 1}).name
+		item_c = make_item(properties={"is_stock_item": 1}).name
+		warehouse = create_warehouse("_Test Multi Balance WH A")
+
+		for item_code, qty in ((item_a, 10), (item_b, 25), (item_c, 7)):
+			make_stock_entry(
+				item_code=item_code, to_warehouse=warehouse, qty=qty, rate=100, posting_date="2026-06-01"
+			)
+
+		data = self.run_report(item_code=[item_a, item_b], warehouse=warehouse)
+
+		balances = {row[0]: row[-1] for row in data}
+		self.assertEqual(balances.get(item_a), 10)
+		self.assertEqual(balances.get(item_b), 25)
+		self.assertNotIn(item_c, balances)