feat: add tested dependency updates with runtime rollback

tests/test_maintenance.py

@@ -0,0 +1,64 @@
+"""Transaction tests: a failed health check must never leave the candidate active."""
+import logging
+from pathlib import Path
+import tempfile
+import unittest
+from unittest.mock import patch
+
+from jr_einvoice.maintenance import Maintenance, locked, point
+
+
+class MaintenanceTest(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self.tmp.cleanup)
+        self.root = Path(self.tmp.name)
+        self.maintenance = Maintenance(self.root, logging.getLogger('maintenance-test'))
+        self.state = self.maintenance.state
+        self.state.mkdir()
+        self.old = self.state / 'old'
+        self.new = self.state / 'new'
+        self.old.mkdir()
+        self.new.mkdir()
+        point(self.state / 'current', self.old)
+
+    def test_success_and_manual_rollback(self):
+        with patch.object(self.maintenance, 'health'):
+            self.maintenance.activate(self.new)
+            self.assertEqual((self.state / 'current').resolve(), self.new)
+            self.maintenance.rollback()
+        self.assertEqual((self.state / 'current').resolve(), self.old)
+        self.assertEqual((self.state / 'previous').resolve(), self.new)
+
+    def test_post_activation_failure_and_interrupt_restore_old(self):
+        for failure in (RuntimeError('bad invoice'), KeyboardInterrupt()):
+            with self.subTest(failure=type(failure).__name__):
+                with patch.object(self.maintenance, 'health', side_effect=failure):
+                    with self.assertRaises(type(failure)):
+                        self.maintenance.activate(self.new)
+                self.assertEqual((self.state / 'current').resolve(), self.old)
+
+    def test_failed_rollback_precheck_keeps_active(self):
+        point(self.state / 'previous', self.new)
+        with patch.object(self.maintenance, 'health', side_effect=RuntimeError('bad')):
+            with self.assertRaises(RuntimeError):
+                self.maintenance.rollback()
+        self.assertEqual((self.state / 'current').resolve(), self.old)
+
+    def test_parallel_update_is_rejected(self):
+        with locked(self.state):
+            with self.assertRaisesRegex(RuntimeError, 'anderer'):
+                with locked(self.state):
+                    self.fail('lock not enforced')
+
+    def test_download_failure_never_switches(self):
+        with patch.object(self.maintenance, 'run'), patch('jr_einvoice.maintenance.install_mustang', side_effect=RuntimeError('checksum')):
+            with self.assertRaises(RuntimeError):
+                self.maintenance.update(True, '2.26.0')
+        self.assertEqual((self.state / 'current').resolve(), self.old)
+
+    def test_invalid_version_is_rejected_before_commands(self):
+        with patch.object(self.maintenance, 'run') as run:
+            with self.assertRaises(ValueError):
+                self.maintenance.update(True, '../bad')
+            run.assert_not_called()