tests: explicit sync on self.app instance ready and make sure _testcase_event is cleared before

QMetaObject.invokeMethod as that can race if it gets inadvertently executed synchronously.

tests/qt_util.py

@@ -4,7 +4,7 @@ import unittest
 from functools import wraps, partial
 from unittest import SkipTest
 
-from PyQt6.QtCore import QCoreApplication, QTimer, QMetaObject, Qt, pyqtSlot, QObject
+from PyQt6.QtCore import QCoreApplication, QMetaObject, Qt, pyqtSlot, QObject
 
 
 class TestQCoreApplication(QCoreApplication):
@@ -33,42 +33,48 @@ class QEventReceiver(QObject):
         self.received.clear()
 
 
-class QETestCase(unittest.IsolatedAsyncioTestCase):
+class QETestCase(unittest.TestCase):
 
     def setUp(self):
         super().setUp()
         self.app = None
         self._e = None
-        self._event = threading.Event()
+        self._testcase_event = threading.Event()
+        self._app_ready_event = threading.Event()
 
         def start_qt_task():
-            self.app = TestQCoreApplication([])
-
-            # self.timer = QTimer(self.app)
-            # self.timer.setSingleShot(False)
-            # self.timer.setInterval(500)  # msec
-            # self.timer.timeout.connect(lambda: None)  # periodically enter python scope
-
-            self.app.exec()
-            self.app = None
-
-        self.qt_thread = threading.Thread(target=start_qt_task)
-        self.qt_thread.start()
+            try:
+                assert self.app is None
+                self.app = TestQCoreApplication([])
+                self._app_ready_event.set()
+                self.app.exec()
+                self.app = None
+            except Exception as e:
+                print(f'Problem starting QCoreApplication: {str(e)}')
+
+        self._qt_thread = threading.Thread(target=start_qt_task)
+        self._qt_thread.start()
 
     def tearDown(self):
         self.app.exit()
-        if self.qt_thread.is_alive():
-            self.qt_thread.join()
+        if self._qt_thread.is_alive():
+            self._qt_thread.join()
 
 
 def qt_test(func):
     @wraps(func)
     def decorator(self, *args):
         if threading.current_thread().name == 'MainThread':
+            res = self._app_ready_event.wait(3)
+            if not res:
+                raise Exception('app not ready in time')
+            self._testcase_event.clear()
             self.app._instance = self
             self.app._method = func.__name__
             QMetaObject.invokeMethod(self.app, 'doInvoke', Qt.ConnectionType.QueuedConnection)
-            self._event.wait(15)
+            res = self._testcase_event.wait(15)
+            if not res:
+                self._e = Exception('testcase timed out')
             if self._e:
                 print("".join(traceback.format_exception(self._e)))
                 # deallocate stored exception from qt thread otherwise we SEGV garbage collector
@@ -88,6 +94,5 @@ def qt_test(func):
         except Exception as e:
             self._e = e
         finally:
-            self._event.set()
-            self._event.clear()
+            self._testcase_event.set()
     return decorator