test: ensure all toplevelwidgets are closed

tests/unit_tests/conftest.py

@@ -1,4 +1,6 @@
 import pytest
+from pytestqt.exceptions import TimeoutError as QtBotTimeoutError
+from qtpy.QtWidgets import QApplication
 
 from bec_widgets.cli.rpc_register import RPCRegister
 from bec_widgets.qt_utils import error_popups
@@ -6,9 +8,16 @@ from bec_widgets.utils import bec_dispatcher as bec_dispatcher_module
 
 
 @pytest.fixture(autouse=True)
-def qapplication(qapp):  # pylint: disable=unused-argument
+def qapplication(qtbot):  # pylint: disable=unused-argument
     yield
-    qapp.processEvents()  # make sure all events are processed before shutting down
+
+    qapp = QApplication.instance()
+    qapp.quit()
+    qapp.processEvents()
+    try:
+        qtbot.waitUntil(lambda: qapp.topLevelWidgets() == [])
+    except QtBotTimeoutError as exc:
+        raise TimeoutError(f"Failed to close all widgets: {qapp.topLevelWidgets()}") from exc
 
 
 @pytest.fixture(autouse=True)
@@ -31,3 +40,25 @@ def bec_dispatcher(threads_check):  # pylint: disable=unused-argument
 @pytest.fixture(autouse=True)
 def clean_singleton():
     error_popups._popup_utility_instance = None
+
+
+def create_widget(qtbot, widget, *args, **kwargs):
+    """
+    Create a widget and add it to the qtbot for testing. This is a helper function that
+    should be used in all tests that require a widget to be created.
+    DO NOT CREATE WIDGETS DIRECTLY IN A FIXTURE!
+
+    Args:
+        qtbot (fixture): pytest-qt fixture
+        widget (QWidget): widget class to be created
+        *args: positional arguments for the widget
+        **kwargs: keyword arguments for the widget
+
+    Returns:
+        QWidget: the created widget
+
+    """
+    widget = widget(*args, **kwargs)
+    qtbot.addWidget(widget)
+    qtbot.waitExposed(widget)
+    return widget