orphan disk search update

tests/test-orphan-disks.py

@@ -90,6 +90,29 @@ class ReportTests(unittest.TestCase):
         with self.assertRaises(FileExistsError):
             disks.export_csv(path, [])
 
+    def test_csv_filename_extensions(self):
+        for name, expected in [('report', 'report.csv'), ('uppercase.CSV', 'uppercase.CSV'),
+                               ('report.txt', 'report.txt.csv')]:
+            with self.subTest(name=name):
+                saved = disks.export_csv(self.root / name, [])
+                self.assertEqual(saved, self.root / expected)
+                self.assertTrue(saved.is_file())
+
+    def test_csv_folder_default_and_collisions(self):
+        from datetime import datetime
+        from unittest.mock import patch
+        with patch.object(disks, 'datetime') as clock:
+            clock.now.return_value = datetime(2026, 9, 22, 14, 30, 59)
+            first = disks.export_csv(self.root, [])
+            original = first.read_text()
+            second = disks.export_csv(str(self.root) + '/', [])
+            self.assertEqual(first.name, 'tapm-orphan-disks-2026-09-22-143059.csv')
+            self.assertEqual(second.name, 'tapm-orphan-disks-2026-09-22-143059-1.csv')
+            self.assertEqual(first.read_text(), original)
+            nested = disks.export_csv(str(self.root / 'new-folder') + '/', [])
+            self.assertTrue(nested.is_file())
+            self.assertEqual(nested.parent, self.root / 'new-folder')
+
     def test_disk_sizes_in_display_and_csv(self):
         for index, (size, expected) in enumerate([
                 (4 * 1024 ** 2, '4.00 MiB'),