test: add coverage for Stock Qty vs Batch Qty report

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

erpnext/stock/report/stock_qty_vs_batch_qty/test_stock_qty_vs_batch_qty.py

@@ -0,0 +1,67 @@
+# 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.report.stock_qty_vs_batch_qty.stock_qty_vs_batch_qty import execute
+from erpnext.tests.utils import ERPNextTestSuite
+
+
+class TestStockQtyVsBatchQty(ERPNextTestSuite):
+	def run_report(self, **extra):
+		return execute(frappe._dict({"company": "_Test Company", **extra}))[1]
+
+	def make_batch_item(self):
+		return make_item(
+			properties={
+				"is_stock_item": 1,
+				"has_batch_no": 1,
+				"create_new_batch": 1,
+				"batch_number_series": "SQB-.#####",
+			}
+		).name
+
+	def rows_for_item(self, data, item):
+		return [row for row in data if row["item_code"] == item]
+
+	def test_stock_qty_matches_batch_qty(self):
+		item = self.make_batch_item()
+		make_stock_entry(
+			item_code=item,
+			to_warehouse="_Test Warehouse - _TC",
+			qty=10,
+			rate=100,
+			posting_date="2026-06-01",
+		)
+
+		# The report only lists batches where stock qty and batch qty differ.
+		# A healthy item has difference == 0, so it must be absent from results.
+		data = self.run_report(item=item)
+		self.assertEqual(self.rows_for_item(data, item), [])
+
+	def test_mismatch_reports_difference(self):
+		item = self.make_batch_item()
+		make_stock_entry(
+			item_code=item,
+			to_warehouse="_Test Warehouse - _TC",
+			qty=10,
+			rate=100,
+			posting_date="2026-06-01",
+		)
+		batch_no = frappe.db.get_value("Batch", {"item": item}, "name")
+		self.assertTrue(batch_no)
+
+		# Corrupt the stored batch qty so it no longer matches actual stock qty (10).
+		frappe.db.set_value("Batch", batch_no, "batch_qty", 7)
+
+		data = self.run_report(item=item, batch=batch_no)
+		rows = self.rows_for_item(data, item)
+		self.assertEqual(len(rows), 1)
+
+		row = rows[0]
+		self.assertEqual(row["batch"], batch_no)
+		self.assertEqual(row["batch_qty"], 7)
+		self.assertEqual(row["stock_qty"], 10)
+		self.assertEqual(row["difference"], 3)