test: add coverage for Bisect Accounting Statements bisection

erpnext/accounts/doctype/bisect_accounting_statements/test_bisect_accounting_statements.py

@@ -1,11 +1,47 @@
-# Copyright (c) 2023, Frappe Technologies Pvt. Ltd. and Contributors
+# Copyright (c) 2026, Frappe Technologies Pvt. Ltd. and Contributors
 # See license.txt
 
-# import frappe
+import datetime
 
+import frappe
+from frappe.utils import getdate
 
 from erpnext.tests.utils import ERPNextTestSuite
 
 
 class TestBisectAccountingStatements(ERPNextTestSuite):
-	pass
+	"""The tool bisects a date range into a tree of Bisect Nodes down to single days.
+	These cover the date validation and that the bisection cleanly partitions the range."""
+
+	def setUp(self):
+		frappe.set_user("Administrator")
+		frappe.db.delete("Bisect Nodes")
+
+	def _leaf_days(self):
+		leaves = frappe.get_all(
+			"Bisect Nodes",
+			filters={"left_child": ["is", "not set"]},
+			fields=["period_from_date", "period_to_date"],
+		)
+		# every leaf spans a single day
+		for leaf in leaves:
+			self.assertEqual(getdate(leaf.period_from_date), getdate(leaf.period_to_date))
+		return sorted(getdate(leaf.period_from_date) for leaf in leaves)
+
+	def test_validate_dates_rejects_reversed_range(self):
+		doc = frappe.new_doc("Bisect Accounting Statements")
+		doc.from_date = "2026-01-08"
+		doc.to_date = "2026-01-01"
+		self.assertRaises(frappe.ValidationError, doc.validate)
+
+	def test_bfs_partitions_range_into_single_days(self):
+		doc = frappe.new_doc("Bisect Accounting Statements")
+		doc.bfs(datetime.datetime(2026, 1, 1), datetime.datetime(2026, 1, 8))
+
+		# the 8-day span Jan 1..Jan 8 becomes exactly 8 contiguous single-day leaves
+		self.assertEqual(self._leaf_days(), [getdate(f"2026-01-0{n}") for n in range(1, 9)])
+
+	def test_dfs_produces_the_same_partition_as_bfs(self):
+		doc = frappe.new_doc("Bisect Accounting Statements")
+		doc.dfs(datetime.datetime(2026, 1, 1), datetime.datetime(2026, 1, 8))
+		self.assertEqual(self._leaf_days(), [getdate(f"2026-01-0{n}") for n in range(1, 9)])