fix(update): harden reentry state and add runtime regression test

tests/test_update_reentry_runtime.py

@@ -0,0 +1,97 @@
+import unittest
+from types import SimpleNamespace
+from unittest import mock
+
+
+class _DummySignal:
+    def __init__(self):
+        self._callbacks = []
+
+    def connect(self, callback):
+        if callback is not None:
+            self._callbacks.append(callback)
+
+    def emit(self, *args, **kwargs):
+        for callback in list(self._callbacks):
+            callback(*args, **kwargs)
+
+
+class _DummyThread:
+    created = 0
+
+    def __init__(self, _parent=None):
+        type(self).created += 1
+        self.started = _DummySignal()
+        self.finished = _DummySignal()
+
+    def start(self):
+        self.started.emit()
+
+    def quit(self):
+        self.finished.emit()
+
+    def deleteLater(self):
+        return None
+
+
+class _DummyChecker:
+    created = 0
+
+    def __init__(self, *_args, **_kwargs):
+        type(self).created += 1
+        self.check_finished = _DummySignal()
+        self.check_failed = _DummySignal()
+
+    def moveToThread(self, _thread):
+        return None
+
+    def run(self):
+        return None
+
+    def deleteLater(self):
+        return None
+
+
+class UpdateReentryRuntimeTests(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        try:
+            import main  # noqa: PLC0415
+        except Exception as exc:
+            raise unittest.SkipTest(f"main import unavailable: {exc}") from exc
+        cls.main = main
+
+    def test_repeated_update_check_is_ignored_until_thread_finishes(self):
+        _DummyChecker.created = 0
+        _DummyThread.created = 0
+        manager = self.main.VkChatManager.__new__(self.main.VkChatManager)
+        manager._update_in_progress = False
+        manager._update_check_silent = False
+        manager.update_channel = "stable"
+        manager.update_repository_url = "https://example.com/org/repo"
+        manager.update_checker = None
+        manager.update_thread = None
+        manager.status_label = SimpleNamespace(setText=lambda *_args, **_kwargs: None)
+        manager._log_event = lambda *_args, **_kwargs: None
+        manager._set_update_action_state = lambda *_args, **_kwargs: None
+
+        with mock.patch.object(self.main, "UpdateChecker", _DummyChecker), mock.patch.object(self.main, "QThread", _DummyThread):
+            self.main.VkChatManager.check_for_updates(manager, silent_no_updates=True)
+            self.assertTrue(manager._update_in_progress)
+            self.assertEqual(_DummyChecker.created, 1)
+            self.assertEqual(_DummyThread.created, 1)
+            first_thread = manager.update_thread
+
+            self.main.VkChatManager.check_for_updates(manager, silent_no_updates=True)
+            self.assertEqual(_DummyChecker.created, 1)
+            self.assertEqual(_DummyThread.created, 1)
+            self.assertIs(manager.update_thread, first_thread)
+
+            manager.update_checker.check_finished.emit({"has_update": False, "current_version": self.main.APP_VERSION})
+            self.assertFalse(manager._update_in_progress)
+            self.assertIsNone(manager.update_checker)
+            self.assertIsNone(manager.update_thread)
+
+
+if __name__ == "__main__":
+    unittest.main()