refactor(tests): ensure BEC dispatcher singleton object is renewed at each test

and add a check for dangling threads

bec_widgets/examples/modular_app/modular_app.py

@@ -3,6 +3,7 @@ import os
 from qtpy import uic
 from qtpy.QtWidgets import QMainWindow, QApplication
 
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 from bec_widgets.widgets import BECMonitor
 
 # some default configs for demonstration purposes
@@ -166,7 +167,7 @@ class ModularApp(QMainWindow):
         super(ModularApp, self).__init__(parent)
 
         # Client and device manager from BEC
-        self.client = bec_dispatcher.client if client is None else client
+        self.client = BECDispatcher().client if client is None else client
 
         # Loading UI
         current_path = os.path.dirname(__file__)
@@ -187,10 +188,8 @@ class ModularApp(QMainWindow):
 
 
 if __name__ == "__main__":
-    from bec_widgets.utils.bec_dispatcher import bec_dispatcher
-
     # BECclient global variables
-    client = bec_dispatcher.client
+    client = BECDispatcher().client
     client.start()
 
     app = QApplication([])

bec_widgets/examples/oneplot/oneplot.py

@@ -10,6 +10,7 @@ from pyqtgraph import mkBrush, mkColor, mkPen
 from pyqtgraph.Qt import QtCore, uic
 
 from bec_widgets.utils import Crosshair, ctrl_c
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 
 # TODO implement:
@@ -239,8 +240,6 @@ class PlotApp(QWidget):
 if __name__ == "__main__":
     import yaml
 
-    from bec_widgets.utils.bec_dispatcher import bec_dispatcher
-
     with open("config_noworker.yaml", "r") as file:
         config = yaml.safe_load(file)
 
@@ -251,6 +250,7 @@ if __name__ == "__main__":
     dap_worker = None if dap_worker == "None" else dap_worker
 
     # BECclient global variables
+    bec_dispatcher = BECDispatcher()
     client = bec_dispatcher.client
     client.start()
 

bec_widgets/examples/plot_app/plot_app.py

@@ -23,6 +23,7 @@ from pyqtgraph.Qt import QtWidgets
 
 from bec_lib import MessageEndpoints
 from bec_widgets.utils import Crosshair, Colors
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 
 # TODO implement:
@@ -92,7 +93,7 @@ class PlotApp(QWidget):
         self.error_handler = ErrorHandler(parent=self)
 
         # Client and device manager from BEC
-        self.client = bec_dispatcher.client if client is None else client
+        self.client = BECDispatcher().client if client is None else client
         self.dev = self.client.device_manager.devices
 
         # Loading UI
@@ -692,8 +693,6 @@ if __name__ == "__main__":
     import argparse
 
     # from bec_widgets import ctrl_c
-    from bec_widgets.utils.bec_dispatcher import bec_dispatcher
-
     parser = argparse.ArgumentParser(description="Plotting App")
     parser.add_argument(
         "--config",
@@ -715,6 +714,7 @@ if __name__ == "__main__":
         exit(1)
 
     # BECclient global variables
+    bec_dispatcher = BECDispatcher()
     client = bec_dispatcher.client
     client.start()
 

bec_widgets/examples/stream_plot/stream_plot.py

@@ -13,9 +13,7 @@ from pyqtgraph import mkBrush, mkPen
 from pyqtgraph.Qt import QtCore, QtWidgets, uic
 from pyqtgraph.Qt.QtCore import pyqtSignal
 from bec_widgets.utils import Crosshair, Colors
-from bec_widgets.utils.bec_dispatcher import bec_dispatcher
-
-# client = bec_dispatcher.client
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 
 class StreamPlot(QtWidgets.QWidget):
@@ -32,7 +30,7 @@ class StreamPlot(QtWidgets.QWidget):
         """
 
         # Client and device manager from BEC
-        self.client = bec_dispatcher.client if client is None else client
+        self.client = BECDispatcher().client if client is None else client
 
         super(StreamPlot, self).__init__()
         # Set style for pyqtgraph plots
@@ -314,6 +312,7 @@ if __name__ == "__main__":
     print(f"Plotting signals for: {', '.join(value.signals)}")
 
     # Client from dispatcher
+    bec_dispatcher = BECDispatcher()
     client = bec_dispatcher.client
 
     app = QtWidgets.QApplication([])

bec_widgets/utils/bec_dispatcher.py

@@ -90,6 +90,16 @@ class _BECDispatcher(QObject):
         consumer.start()
         return _Connection(consumer)
 
+    def _do_disconnect_slot(self, topic, slot):
+        connection = self._connections[topic]
+        connection.signal.disconnect(slot)
+        connection.slots.remove(slot)
+        if not connection.slots:
+            print(f"{connection.consumer} is shutting down")
+            connection.consumer.shutdown()
+            connection.consumer.join()
+            del self._connections[topic]
+
     def _disconnect_slot_from_topic(self, slot: Callable, topic: str) -> None:
         """A helper method to disconnect a slot from a specific topic.
 
@@ -100,11 +110,7 @@ class _BECDispatcher(QObject):
         """
         connection = self._connections.get(topic)
         if connection and slot in connection.slots:
-            connection.signal.disconnect(slot)
-            connection.slots.remove(slot)
-            if not connection.slots:
-                connection.consumer.shutdown()
-                del self._connections[topic]
+            self._do_disconnect_slot(topic, slot)
 
     def disconnect_slot(self, slot: Callable, topics: Union[str, list]) -> None:
         """Disconnect widget's pyqt slot from pub/sub updates on a topic.
@@ -123,12 +129,7 @@ class _BECDispatcher(QObject):
                 if common_topics:
                     remaining_topics = set(key) - set(topics)
                     # Disconnect slot from common topics
-                    connection.signal.disconnect(slot)
-                    connection.slots.remove(slot)
-                    if not connection.slots:
-                        print(f"{connection.consumer} is shutting down")
-                        connection.consumer.shutdown()
-                        del self._connections[key]
+                    self._do_disconnect_slot(key, slot)
                     # Reconnect slot to remaining topics if any
                     if remaining_topics:
                         self.connect_slot(slot, list(remaining_topics), True)
@@ -139,13 +140,17 @@ class _BECDispatcher(QObject):
             for slot in list(connection.slots):
                 self._disconnect_slot_from_topic(slot, key)
 
-            if key in self._connections and not connection.slots:
-                connection.consumer.shutdown()
-                del self._connections[key]
+
+# variable holding the Singleton instance of BECDispatcher
+_bec_dispatcher = None
 
 
-parser = argparse.ArgumentParser()
-parser.add_argument("--bec-config", default=None)
-args, _ = parser.parse_known_args()
+def BECDispatcher():
+    global _bec_dispatcher
+    if _bec_dispatcher is None:
+        parser = argparse.ArgumentParser()
+        parser.add_argument("--bec-config", default=None)
+        args, _ = parser.parse_known_args()
 
-bec_dispatcher = _BECDispatcher(args.bec_config)
+        _bec_dispatcher = _BECDispatcher(args.bec_config)
+    return _bec_dispatcher

bec_widgets/widgets/monitor/monitor.py

@@ -12,7 +12,7 @@ from qtpy.QtWidgets import QApplication, QMessageBox
 
 from bec_widgets.utils import Colors, Crosshair, yaml_dialog
 from bec_widgets.validation import MonitorConfigValidator
-from bec_widgets.utils.bec_dispatcher import bec_dispatcher
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 # just for demonstration purposes if script run directly
 CONFIG_SCAN_MODE = {
@@ -282,6 +282,7 @@ class BECMonitor(pg.GraphicsLayoutWidget):
 
         # Client and device manager from BEC
         self.plot_data = None
+        bec_dispatcher = BECDispatcher()
         self.client = bec_dispatcher.client if client is None else client
         self.dev = self.client.device_manager.devices
         self.queue = self.client.queue
@@ -824,7 +825,7 @@ if __name__ == "__main__":  # pragma: no cover
     else:
         config = CONFIG_SIMPLE
 
-    client = bec_dispatcher.client
+    client = BECDispatcher().client
     client.start()
     app = QApplication(sys.argv)
     monitor = BECMonitor(

bec_widgets/widgets/motor_map/motor_map.py

@@ -14,7 +14,7 @@ from qtpy.QtCore import Slot as pyqtSlot
 from qtpy.QtWidgets import QApplication
 
 from bec_widgets.utils.yaml_dialog import load_yaml
-from bec_widgets.utils.bec_dispatcher import bec_dispatcher
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 CONFIG_DEFAULT = {
     "plot_settings": {
@@ -63,6 +63,7 @@ class MotorMap(pg.GraphicsLayoutWidget):
         super().__init__(parent=parent)
 
         # Import BEC related stuff
+        bec_dispatcher = BECDispatcher()
         self.client = bec_dispatcher.client if client is None else client
         self.dev = self.client.device_manager.devices
 
@@ -172,6 +173,7 @@ class MotorMap(pg.GraphicsLayoutWidget):
         """Connect motors to slots."""
 
         # Disconnect all slots before connecting a new ones
+        bec_dispatcher = BECDispatcher()
         bec_dispatcher.disconnect_all()
 
         # Get list of all unique motors
@@ -541,7 +543,7 @@ if __name__ == "__main__":  # pragma: no cover
     else:
         config = CONFIG_DEFAULT
 
-    client = bec_dispatcher.client
+    client = BECDispatcher().client
     client.start()
     app = QApplication(sys.argv)
     motor_map = MotorMap(

bec_widgets/widgets/scan_control/scan_control.py

@@ -22,6 +22,7 @@ from qtpy.QtWidgets import (
 
 from bec_lib import MessageEndpoints
 from bec_widgets.utils.widget_io import WidgetIO
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 
 class ScanArgType:
@@ -45,7 +46,7 @@ class ScanControl(QWidget):
         super().__init__(parent)
 
         # Client from BEC + shortcuts to device manager and scans
-        self.client = bec_dispatcher.client if client is None else client
+        self.client = BECDispatcher().client if client is None else client
         self.dev = self.client.device_manager.devices
         self.scans = self.client.scans
 
@@ -425,10 +426,8 @@ class ScanControl(QWidget):
 
 # Application example
 if __name__ == "__main__":  # pragma: no cover
-    from bec_widgets.utils.bec_dispatcher import bec_dispatcher
-
     # BECclient global variables
-    client = bec_dispatcher.client
+    client = BECDispatcher().client
     client.start()
 
     app = QApplication([])

bec_widgets/widgets/scan_plot/scan2d_plot.py

@@ -6,7 +6,7 @@ from bec_lib import MessageEndpoints
 from bec_lib.logger import bec_logger
 from qtpy.QtCore import Property as pyqtProperty, Slot as pyqtSlot
 
-from bec_widgets.utils.bec_dispatcher import bec_dispatcher
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 logger = bec_logger.logger
 
@@ -17,7 +17,7 @@ pg.setConfigOptions(background="w", foreground="k", antialias=True)
 class BECScanPlot2D(pg.GraphicsView):
     def __init__(self, parent=None, background="default"):
         super().__init__(parent, background)
-        bec_dispatcher.connect_slot(self.on_scan_segment, MessageEndpoints.scan_segment())
+        BECDispatcher().connect_slot(self.on_scan_segment, MessageEndpoints.scan_segment())
 
         self._scanID = None
         self._scanID_lock = RLock()

bec_widgets/widgets/scan_plot/scan_plot.py

@@ -6,7 +6,7 @@ from bec_lib import MessageEndpoints
 from bec_lib.logger import bec_logger
 from qtpy.QtCore import Property as pyqtProperty, Slot as pyqtSlot
 
-from bec_widgets.utils.bec_dispatcher import bec_dispatcher
+from bec_widgets.utils.bec_dispatcher import BECDispatcher
 
 logger = bec_logger.logger
 
@@ -18,7 +18,7 @@ COLORS = ["#fd7f6f", "#7eb0d5", "#b2e061", "#bd7ebe", "#ffb55a"]
 class BECScanPlot(pg.GraphicsView):
     def __init__(self, parent=None, background="default"):
         super().__init__(parent, background)
-        bec_dispatcher.connect_slot(self.on_scan_segment, MessageEndpoints.scan_segment())
+        BECDispatcher().connect_slot(self.on_scan_segment, MessageEndpoints.scan_segment())
 
         self.view = pg.PlotItem()
         self.setCentralItem(self.view)
@@ -94,6 +94,7 @@ class BECScanPlot(pg.GraphicsView):
 
     @y_channel_list.setter
     def y_channel_list(self, new_list):
+        bec_dispatcher = BECDispatcher()
         # TODO: do we want to care about dap/not dap here?
         chan_removed = [chan for chan in self._y_channel_list if chan not in new_list]
         if chan_removed and chan_removed[0].startswith("dap."):

tests/conftest.py

@@ -0,0 +1,32 @@
+import pytest
+import threading
+
+from bec_widgets.utils import bec_dispatcher as bec_dispatcher_module
+
+
+@pytest.fixture()
+def threads_check():
+    current_threads = set(
+        th
+        for th in threading.enumerate()
+        if "loguru" not in th.name and th is not threading.main_thread()
+    )
+    yield
+    threads_after = set(
+        th
+        for th in threading.enumerate()
+        if "loguru" not in th.name and th is not threading.main_thread()
+    )
+    additional_threads = threads_after - current_threads
+    assert (
+        len(additional_threads) == 0
+    ), f"Test creates {len(additional_threads)} threads that are not cleaned: {additional_threads}"
+
+
+@pytest.fixture(autouse=True)
+def bec_dispatcher(threads_check):
+    bec_dispatcher = bec_dispatcher_module.BECDispatcher()
+    yield bec_dispatcher
+    bec_dispatcher.disconnect_all()
+    # reinitialize singleton for next test
+    bec_dispatcher_module._bec_dispatcher = None

tests/test_bec_dispatcher.py

@@ -5,18 +5,10 @@ import pytest
 from bec_lib.messages import ScanMessage
 from bec_lib.connector import MessageObject
 
-# TODO: find a better way to mock singletons
-from bec_widgets.utils.bec_dispatcher import _BECDispatcher
 
 msg = MessageObject(topic="", value=ScanMessage(point_id=0, scanID=0, data={}).dumps())
 
 
-@pytest.fixture(name="bec_dispatcher")
-def _bec_dispatcher():
-    bec_dispatcher = _BECDispatcher()
-    yield bec_dispatcher
-
-
 @pytest.fixture(name="consumer")
 def _consumer(bec_dispatcher):
     bec_dispatcher.client.connector.consumer = Mock()