test: add coverage for Stock Ledger Invariant Check report

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

erpnext/stock/report/stock_ledger_invariant_check/test_stock_ledger_invariant_check.py

@@ -0,0 +1,44 @@
+# 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_ledger_invariant_check.stock_ledger_invariant_check import execute
+from erpnext.tests.utils import ERPNextTestSuite
+
+WAREHOUSE = "_Test Warehouse - _TC"
+COMPANY = "_Test Company"
+
+
+class TestStockLedgerInvariantCheck(ERPNextTestSuite):
+	def run_report(self, **extra):
+		filters = frappe._dict({"company": COMPANY, "warehouse": WAREHOUSE})
+		filters.update(extra)
+		return execute(filters)[1]
+
+	def make_movements(self) -> str:
+		item = make_item(properties={"is_stock_item": 1, "valuation_method": "FIFO"}).name
+		make_stock_entry(item_code=item, to_warehouse=WAREHOUSE, qty=10, rate=100, posting_date="2026-06-01")
+		make_stock_entry(item_code=item, to_warehouse=WAREHOUSE, qty=5, rate=120, posting_date="2026-06-02")
+		make_stock_entry(item_code=item, from_warehouse=WAREHOUSE, qty=4, rate=0, posting_date="2026-06-03")
+		return item
+
+	def test_diagnostic_rows_have_no_discrepancy(self):
+		item = self.make_movements()
+
+		data = self.run_report(item_code=item)
+
+		self.assertEqual(len(data), 3)
+		for row in data:
+			self.assertLess(abs(row.difference_in_qty), 0.01)
+			self.assertLess(abs(row.fifo_qty_diff), 0.01)
+			self.assertLess(abs(row.diff_value_diff), 0.01)
+
+	def test_running_balance_matches(self):
+		item = self.make_movements()
+
+		data = self.run_report(item_code=item)
+
+		self.assertEqual(data[-1].qty_after_transaction, 11)