diff --git a/bec_widgets/tests/utils.py b/bec_widgets/tests/utils.py
index 0b47f367e..8b50b3796 100644
--- a/bec_widgets/tests/utils.py
+++ b/bec_widgets/tests/utils.py
@@ -1,6 +1,7 @@
 # pylint: skip-file
 from unittest.mock import MagicMock
 
+from bec_lib.config_helper import ConfigHelper
 from bec_lib.device import Device as BECDevice
 from bec_lib.device import Positioner as BECPositioner
 from bec_lib.device import ReadoutPriority
@@ -219,7 +220,9 @@ def __init__(self, name, enabled=True):
 
 
 class DMMock:
-    def __init__(self):
+    def __init__(self, *args, **kwargs):
+        self._service = args[0]
+        self.config_helper = ConfigHelper(self._service.connector, self._service._service_name)
         self.devices = DeviceContainer()
         self.enabled_devices = [device for device in self.devices if device.enabled]
 
@@ -273,6 +276,10 @@ def _get_redis_device_config(self) -> list[dict]:
             configs.append(device._config)
         return configs
 
+    def initialize(*_): ...
+
+    def shutdown(self): ...
+
 
 DEVICES = [
     FakePositioner("samx", limits=[-10, 10], read_value=2.0),
diff --git a/bec_widgets/utils/bec_dispatcher.py b/bec_widgets/utils/bec_dispatcher.py
index 8c5690c19..08a26f150 100644
--- a/bec_widgets/utils/bec_dispatcher.py
+++ b/bec_widgets/utils/bec_dispatcher.py
@@ -123,17 +123,16 @@ def __init__(self, client=None, config: str | ServiceConfig | None = None, gui_i
         self._registered_slots: DefaultDict[Hashable, QtThreadSafeCallback] = (
             collections.defaultdict()
         )
-        self.client = client
 
-        if self.client is None:
-            if config is not None:
-                if not isinstance(config, ServiceConfig):
-                    # config is supposed to be a path
-                    config = ServiceConfig(config)
+        if client is None:
+            if config is not None and not isinstance(config, ServiceConfig):
+                # config is supposed to be a path
+                config = ServiceConfig(config)
             self.client = BECClient(
                 config=config, connector_cls=QtRedisConnector, name="BECWidgets"
             )
         else:
+            self.client = client
             if self.client.started:
                 # have to reinitialize client to use proper connector
                 logger.info("Shutting down BECClient to switch to QtRedisConnector")
diff --git a/bec_widgets/widgets/containers/explorer/script_tree_widget.py b/bec_widgets/widgets/containers/explorer/script_tree_widget.py
index 68ff10353..d71952283 100644
--- a/bec_widgets/widgets/containers/explorer/script_tree_widget.py
+++ b/bec_widgets/widgets/containers/explorer/script_tree_widget.py
@@ -63,7 +63,7 @@ def __init__(self, parent=None):
         layout.setSpacing(0)
 
         # Create tree view
-        self.tree = QTreeView()
+        self.tree = QTreeView(parent=self)
         self.tree.setHeaderHidden(True)
         self.tree.setRootIsDecorated(True)
 
@@ -71,12 +71,12 @@ def __init__(self, parent=None):
         self.tree.setMouseTracking(True)
 
         # Create file system model
-        self.model = QFileSystemModel()
+        self.model = QFileSystemModel(parent=self)
         self.model.setNameFilters(["*.py"])
         self.model.setNameFilterDisables(False)
 
         # Create proxy model to filter out underscore directories
-        self.proxy_model = QSortFilterProxyModel()
+        self.proxy_model = QSortFilterProxyModel(parent=self)
         self.proxy_model.setFilterRegularExpression(QRegularExpression("^[^_].*"))
         self.proxy_model.setSourceModel(self.model)
         self.tree.setModel(self.proxy_model)
diff --git a/tests/unit_tests/client_mocks.py b/tests/unit_tests/client_mocks.py
index 613119e02..80c056dcb 100644
--- a/tests/unit_tests/client_mocks.py
+++ b/tests/unit_tests/client_mocks.py
@@ -1,47 +1,18 @@
 # pylint: disable = no-name-in-module,missing-class-docstring, missing-module-docstring
 from math import inf
-from unittest.mock import MagicMock, patch
+from unittest.mock import MagicMock, PropertyMock, patch
 
 import fakeredis
 import pytest
 from bec_lib.bec_service import messages
 from bec_lib.endpoints import MessageEndpoints
-from bec_lib.redis_connector import RedisConnector
 from bec_lib.scan_history import ScanHistory
 
-from bec_widgets.tests.utils import DEVICES, DMMock, FakePositioner, Positioner
-
-
-def fake_redis_server(host, port, **kwargs):
-    redis = fakeredis.FakeRedis()
-    return redis
+from bec_widgets.tests.utils import FakePositioner, Positioner
 
 
 @pytest.fixture(scope="function")
 def mocked_client(bec_dispatcher):
-    connector = RedisConnector("localhost:1", redis_cls=fake_redis_server)
-    # Create a MagicMock object
-    client = MagicMock()  # TODO change to real BECClient
-
-    # Shutdown the original client
-    bec_dispatcher.client.shutdown()
-    # Mock the connector attribute
-    bec_dispatcher.client = client
-
-    # Mock the device_manager.devices attribute
-    client.connector = connector
-    client.device_manager = DMMock()
-    client.device_manager.add_devices(DEVICES)
-
-    def mock_mv(*args, relative=False):
-        # Extracting motor and value pairs
-        for i in range(0, len(args), 2):
-            motor = args[i]
-            value = args[i + 1]
-            motor.move(value, relative=relative)
-        return MagicMock(wait=MagicMock())
-
-    client.scans = MagicMock(mv=mock_mv)
 
     # Ensure isinstance check for Positioner passes
     original_isinstance = isinstance
@@ -52,8 +23,8 @@ def isinstance_mock(obj, class_info):
         return original_isinstance(obj, class_info)
 
     with patch("builtins.isinstance", new=isinstance_mock):
-        yield client
-    connector.shutdown()  # TODO change to real BECClient
+        yield bec_dispatcher.client
+    bec_dispatcher.client.connector.shutdown()
 
 
 ##################################################
@@ -190,17 +161,16 @@ def mocked_client_with_dap(mocked_client, dap_plugin_message):
             name="LmfitService1D", status=1, info={}
         ),
     }
-    client = mocked_client
-    client.service_status = dap_services
-    client.connector.set(
+    type(mocked_client).service_status = PropertyMock(return_value=dap_services)
+    mocked_client.connector.set(
         topic=MessageEndpoints.dap_available_plugins("dap"), msg=dap_plugin_message
     )
 
     # Patch the client's DAP attribute so that the available models include "GaussianModel"
     patched_models = {"GaussianModel": {}, "LorentzModel": {}, "SineModel": {}}
-    client.dap._available_dap_plugins = patched_models
+    mocked_client.dap._available_dap_plugins = patched_models
 
-    yield client
+    yield mocked_client
 
 
 class DummyData:
@@ -233,7 +203,6 @@ def create_dummy_scan_item():
             "readout_priority": {"monitored": ["bpm4i"], "async": ["async_device"]},
         }
     }
-    dummy_scan.status_message = MagicMock()
     dummy_scan.status_message.info = {
         "readout_priority": {"monitored": ["bpm4i"], "async": ["async_device"]},
         "scan_report_devices": ["samx"],
diff --git a/tests/unit_tests/conftest.py b/tests/unit_tests/conftest.py
index 6f81a4cf8..2e9b31c95 100644
--- a/tests/unit_tests/conftest.py
+++ b/tests/unit_tests/conftest.py
@@ -1,19 +1,28 @@
 import json
 import time
+from unittest import mock
+from unittest.mock import patch
 
+import fakeredis
 import h5py
 import numpy as np
 import pytest
-from bec_lib import messages
+from bec_lib import messages, service_config
+from bec_lib.bec_service import messages
+from bec_lib.client import BECClient
 from bec_lib.messages import _StoredDataInfo
 from bec_qthemes import apply_theme
+from bec_qthemes._theme import Theme
+from ophyd._pyepics_shim import _dispatcher
 from pytestqt.exceptions import TimeoutError as QtBotTimeoutError
 from qtpy.QtCore import QEvent, QEventLoop
 from qtpy.QtWidgets import QApplication, QMessageBox
 
 from bec_widgets.cli.rpc.rpc_register import RPCRegister
+from bec_widgets.tests.utils import DEVICES, DMMock
 from bec_widgets.utils import bec_dispatcher as bec_dispatcher_module
 from bec_widgets.utils import error_popups
+from bec_widgets.utils.bec_dispatcher import QtRedisConnector
 
 # Patch to set default RAISE_ERROR_DEFAULT to True for tests
 # This means that by default, error popups will raise exceptions during tests
@@ -38,15 +47,20 @@ def process_all_deferred_deletes(qapp):
 def qapplication(qtbot, request, testable_qtimer_class):  # pylint: disable=unused-argument
     qapp = QApplication.instance()
     process_all_deferred_deletes(qapp)
-    apply_theme("light")
-    qapp.processEvents()
+
+    if (
+        not hasattr(qapp, "theme")
+        or not isinstance(qapp.theme, Theme)
+        or qapp.theme.theme != "light"
+    ):
+        apply_theme("light")
+        qapp.processEvents()
 
     yield
 
     # if the test failed, we don't want to check for open widgets as
     # it simply pollutes the output
     # stop pyepics dispatcher for leaking tests
-    from ophyd._pyepics_shim import _dispatcher
 
     _dispatcher.stop()
     if request.node.stash._storage.get("failed"):
@@ -71,9 +85,37 @@ def rpc_register():
     RPCRegister.reset_singleton()
 
 
+_REDIS_CONN: QtRedisConnector | None = None
+
+
+def global_mock_qt_redis_connector(*_, **__):
+    global _REDIS_CONN
+    if _REDIS_CONN is None:
+        _REDIS_CONN = QtRedisConnector(bootstrap="localhost:1", redis_cls=fakeredis.FakeRedis)
+    return _REDIS_CONN
+
+
+def mock_client(*_, **__):
+    with (
+        patch("bec_lib.client.DeviceManagerBase", DMMock),
+        patch("bec_lib.client.DAPPlugins"),
+        patch("bec_lib.client.Scans"),
+        patch("bec_lib.client.ScanManager"),
+        patch("bec_lib.bec_service.BECAccess"),
+    ):
+        client = BECClient(
+            config=service_config.ServiceConfig(config={"redis": {"host": "localhost", "port": 1}}),
+            connector_cls=global_mock_qt_redis_connector,
+        )
+        client.start()
+    client.device_manager.add_devices(DEVICES)
+    return client
+
+
 @pytest.fixture(autouse=True)
 def bec_dispatcher(threads_check):  # pylint: disable=unused-argument
-    bec_dispatcher = bec_dispatcher_module.BECDispatcher()
+    with mock.patch.object(bec_dispatcher_module, "BECClient", mock_client):
+        bec_dispatcher = bec_dispatcher_module.BECDispatcher()
     yield bec_dispatcher
     bec_dispatcher.disconnect_all()
     # clean BEC client
diff --git a/tests/unit_tests/test_abort_button.py b/tests/unit_tests/test_abort_button.py
index d744bd048..44eb76984 100644
--- a/tests/unit_tests/test_abort_button.py
+++ b/tests/unit_tests/test_abort_button.py
@@ -1,5 +1,7 @@
 # pylint: disable=missing-function-docstring, missing-module-docstring, unused-import
 
+from unittest.mock import MagicMock
+
 import pytest
 
 from bec_widgets.widgets.control.buttons.button_abort.button_abort import AbortButton
@@ -10,6 +12,7 @@
 @pytest.fixture
 def abort_button(qtbot, mocked_client):
     widget = AbortButton(client=mocked_client)
+    widget.queue = MagicMock()
     qtbot.addWidget(widget)
     qtbot.waitExposed(widget)
     yield widget
diff --git a/tests/unit_tests/test_bec_dispatcher.py b/tests/unit_tests/test_bec_dispatcher.py
index 69b28a50b..12b57c673 100644
--- a/tests/unit_tests/test_bec_dispatcher.py
+++ b/tests/unit_tests/test_bec_dispatcher.py
@@ -4,10 +4,45 @@
 from unittest import mock
 
 import pytest
+from bec_lib import service_config
 from bec_lib.messages import ScanMessage
 from bec_lib.serialization import MsgpackSerialization
 
-from bec_widgets.utils.bec_dispatcher import QtRedisConnector, QtThreadSafeCallback
+from bec_widgets.utils.bec_dispatcher import BECDispatcher, QtRedisConnector, QtThreadSafeCallback
+
+
+def test_init_handles_client_and_config_arg():
+    # Client passed
+    self_mock = mock.MagicMock(_initialized=False)
+    with mock.patch.object(BECDispatcher, "start_cli_server"):
+        BECDispatcher.__init__(self_mock, client=mock.MagicMock(name="test_client"))
+        assert "test_client" in repr(self_mock.client)
+
+    # No client, service config object
+    self_mock.reset_mock()
+    self_mock._initialized = False
+    with (
+        mock.patch.object(BECDispatcher, "start_cli_server"),
+        mock.patch("bec_widgets.utils.bec_dispatcher.BECClient") as client_cls,
+    ):
+        config = service_config.ServiceConfig()
+        BECDispatcher.__init__(self_mock, client=None, config=config)
+        client_cls.assert_called_with(
+            config=config, connector_cls=QtRedisConnector, name="BECWidgets"
+        )
+
+    # No client, service config string
+    self_mock.reset_mock()
+    self_mock._initialized = False
+    with (
+        mock.patch.object(BECDispatcher, "start_cli_server"),
+        mock.patch("bec_widgets.utils.bec_dispatcher.BECClient"),
+        mock.patch("bec_widgets.utils.bec_dispatcher.ServiceConfig") as svc_cfg,
+        mock.patch("bec_widgets.utils.bec_dispatcher.isinstance", return_value=False),
+    ):
+        config = service_config.ServiceConfig()
+        BECDispatcher.__init__(self_mock, client=None, config="test_str")
+        svc_cfg.assert_called_with("test_str")
 
 
 @pytest.fixture
diff --git a/tests/unit_tests/test_device_browser.py b/tests/unit_tests/test_device_browser.py
index 7c36594ee..f996d96ae 100644
--- a/tests/unit_tests/test_device_browser.py
+++ b/tests/unit_tests/test_device_browser.py
@@ -160,7 +160,7 @@ def test_signal_display(mocked_client, qtbot):
 
 def test_signal_display_no_device(mocked_client, qtbot):
     device_mock = mock.MagicMock()
-    mocked_client.client.device_manager.devices = {"test_device_1": device_mock}
+    mocked_client.device_manager.devices = {"test_device_1": device_mock}
     signal_display = SignalDisplay(client=mocked_client, device="test_device_2")
     qtbot.addWidget(signal_display)
     assert (
diff --git a/tests/unit_tests/test_device_signal_input.py b/tests/unit_tests/test_device_signal_input.py
index 78329344f..fbeb45514 100644
--- a/tests/unit_tests/test_device_signal_input.py
+++ b/tests/unit_tests/test_device_signal_input.py
@@ -146,12 +146,12 @@ def test_signal_lineedit(device_signal_line_edit):
 
 
 def test_device_signal_input_base_cleanup(qtbot, mocked_client):
+    with mock.patch.object(mocked_client.callbacks, "remove"):
+        widget = DeviceInputWidget(client=mocked_client)
+        widget.close()
+        widget.deleteLater()
 
-    widget = DeviceInputWidget(client=mocked_client)
-    widget.close()
-    widget.deleteLater()
-
-    mocked_client.callbacks.remove.assert_called_once_with(widget._device_update_register)
+        mocked_client.callbacks.remove.assert_called_once_with(widget._device_update_register)
 
 
 def test_signal_combobox_get_signal_name_with_item_data(qtbot, device_signal_combobox):
diff --git a/tests/unit_tests/test_scatter_waveform.py b/tests/unit_tests/test_scatter_waveform.py
index f0ba5620a..3a8abcf3b 100644
--- a/tests/unit_tests/test_scatter_waveform.py
+++ b/tests/unit_tests/test_scatter_waveform.py
@@ -1,4 +1,4 @@
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 
 import numpy as np
 
@@ -53,14 +53,16 @@ def test_scatter_waveform_update_with_scan_history(qtbot, mocked_client, monkeyp
     swf = create_widget(qtbot, ScatterWaveform, client=mocked_client)
 
     dummy_scan = create_dummy_scan_item()
+    mocked_client.history = MagicMock()
+    # .get_by_scan_id() typically returns historical data, but we abuse it here
+    # to return mock live data
     mocked_client.history.get_by_scan_id.return_value = dummy_scan
     mocked_client.history.__getitem__.return_value = dummy_scan
 
     swf.plot("samx", "samy", "bpm4i", label="test_curve")
     swf.update_with_scan_history(scan_id="dummy")
-    qtbot.wait(500)
-
-    assert swf.scan_item == dummy_scan
+    qtbot.waitUntil(lambda: swf.scan_item == dummy_scan, timeout=500)
+    qtbot.wait(200)
 
     x_data, y_data = swf.main_curve.getData()
     np.testing.assert_array_equal(x_data, [10, 20, 30])
diff --git a/tests/unit_tests/test_utils_plot_indicators.py b/tests/unit_tests/test_utils_plot_indicators.py
index 6e1b491b2..c156bb38d 100644
--- a/tests/unit_tests/test_utils_plot_indicators.py
+++ b/tests/unit_tests/test_utils_plot_indicators.py
@@ -8,7 +8,7 @@
 
 @pytest.fixture
 def plot_widget_with_arrow_item(qtbot, mocked_client):
-    widget = Waveform(client=mocked_client())
+    widget = Waveform(client=mocked_client)
     qtbot.addWidget(widget)
     qtbot.waitExposed(widget)
 
@@ -17,7 +17,7 @@ def plot_widget_with_arrow_item(qtbot, mocked_client):
 
 @pytest.fixture
 def plot_widget_with_tick_item(qtbot, mocked_client):
-    widget = Waveform(client=mocked_client())
+    widget = Waveform(client=mocked_client)
     qtbot.addWidget(widget)
     qtbot.waitExposed(widget)
 
diff --git a/tests/unit_tests/test_web_console.py b/tests/unit_tests/test_web_console.py
index be49cff11..c27eb516a 100644
--- a/tests/unit_tests/test_web_console.py
+++ b/tests/unit_tests/test_web_console.py
@@ -189,10 +189,10 @@ def test_bec_shell_startup_contains_gui_id(bec_shell_widget):
     assert bec_shell._is_bec_shell
     assert bec_shell._unique_id == "bec_shell"
 
-    assert bec_shell.startup_cmd == "bec --nogui"
+    with mock.patch.object(bec_shell.bec_dispatcher, "cli_server", None):
+        assert bec_shell.startup_cmd == "bec --nogui"
 
-    with mock.patch.object(bec_shell.bec_dispatcher, "cli_server") as mock_cli_server:
-        mock_cli_server.gui_id = "test_gui_id"
+    with mock.patch.object(bec_shell.bec_dispatcher.cli_server, "gui_id", "test_gui_id"):
         assert bec_shell.startup_cmd == "bec --gui-id test_gui_id"