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diff --git a/tests/unit_tests/test_modular_toolbar.py b/tests/unit_tests/test_modular_toolbar.py
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+from typing import Literal
+
+import pytest
+from qtpy.QtCore import Qt
+from qtpy.QtWidgets import QComboBox, QLabel, QToolButton, QWidget
+
+from bec_widgets.qt_utils.toolbar import (
+    DeviceSelectionAction,
+    ExpandableMenuAction,
+    IconAction,
+    MaterialIconAction,
+    ModularToolBar,
+    SeparatorAction,
+    WidgetAction,
+)
+
+
+@pytest.fixture
+def dummy_widget(qtbot):
+    """Fixture to create a simple widget to be used as target widget."""
+    widget = QWidget()
+    qtbot.addWidget(widget)
+    qtbot.waitExposed(widget)
+    return widget
+
+
+@pytest.fixture(params=["horizontal", "vertical"])
+def toolbar_fixture(qtbot, request, dummy_widget):
+    """Parametrized fixture to create a ModularToolBar with different orientations."""
+    orientation: Literal["horizontal", "vertical"] = request.param
+    toolbar = ModularToolBar(
+        target_widget=dummy_widget,
+        orientation=orientation,
+        background_color="rgba(255, 255, 255, 255)",  # White background for testing
+    )
+    qtbot.addWidget(toolbar)
+    qtbot.waitExposed(toolbar)
+    yield toolbar
+    toolbar.close()
+
+
+@pytest.fixture
+def separator_action():
+    """Fixture to create a SeparatorAction."""
+    return SeparatorAction()
+
+
+@pytest.fixture
+def icon_action():
+    """Fixture to create an IconAction."""
+    return IconAction(icon_path="assets/BEC-Icon.png", tooltip="Test Icon Action", checkable=True)
+
+
+@pytest.fixture
+def material_icon_action():
+    """Fixture to create a MaterialIconAction."""
+    return MaterialIconAction(
+        icon_name="home", tooltip="Test Material Icon Action", checkable=False
+    )
+
+
+@pytest.fixture
+def device_selection_action():
+    """Fixture to create a DeviceSelectionAction."""
+    device_combobox = QComboBox()
+    device_combobox.addItems(["Device 1", "Device 2", "Device 3"])
+    device_combobox.setCurrentIndex(0)
+    return DeviceSelectionAction(label="Select Device:", device_combobox=device_combobox)
+
+
+@pytest.fixture
+def widget_action():
+    """Fixture to create a WidgetAction."""
+    sample_widget = QLabel("Sample Widget")
+    return WidgetAction(label="Sample Label:", widget=sample_widget)
+
+
+@pytest.fixture
+def expandable_menu_action():
+    """Fixture to create an ExpandableMenuAction."""
+    action1 = MaterialIconAction(icon_name="counter_1", tooltip="Menu Action 1", checkable=False)
+    action2 = MaterialIconAction(icon_name="counter_2", tooltip="Menu Action 2", checkable=True)
+    actions = {"action1": action1, "action2": action2}
+    return ExpandableMenuAction(
+        label="Expandable Menu", actions=actions, icon_path="assets/BEC-Icon.png"
+    )
+
+
+def test_initialization(toolbar_fixture):
+    """Test that ModularToolBar initializes correctly with different orientations."""
+    toolbar = toolbar_fixture
+    if toolbar.orientation() == Qt.Horizontal:
+        assert toolbar.orientation() == Qt.Horizontal
+    elif toolbar.orientation() == Qt.Vertical:
+        assert toolbar.orientation() == Qt.Vertical
+    else:
+        pytest.fail("Toolbar orientation is neither horizontal nor vertical.")
+    assert toolbar.background_color == "rgba(255, 255, 255, 255)"
+    assert toolbar.widgets == {}
+    assert not toolbar.isMovable()
+    assert not toolbar.isFloatable()
+
+
+def test_set_background_color(toolbar_fixture):
+    """Test setting the background color of the toolbar."""
+    toolbar = toolbar_fixture
+    new_color = "rgba(0, 0, 0, 255)"  # Black
+    toolbar.set_background_color(new_color)
+    assert toolbar.background_color == new_color
+    # Verify stylesheet
+    expected_style = f"QToolBar {{ background-color: {new_color}; border: none; }}"
+    assert toolbar.styleSheet() == expected_style
+
+
+def test_set_orientation(toolbar_fixture, qtbot, dummy_widget):
+    """Test changing the orientation of the toolbar."""
+    toolbar = toolbar_fixture
+    if toolbar.orientation() == Qt.Horizontal:
+        new_orientation = "vertical"
+    else:
+        new_orientation = "horizontal"
+    toolbar.set_orientation(new_orientation)
+    qtbot.wait(100)
+    if new_orientation == "horizontal":
+        assert toolbar.orientation() == Qt.Horizontal
+    else:
+        assert toolbar.orientation() == Qt.Vertical
+
+
+def test_add_action(
+    toolbar_fixture, icon_action, separator_action, material_icon_action, dummy_widget
+):
+    """Test adding different types of actions to the toolbar."""
+    toolbar = toolbar_fixture
+
+    # Add IconAction
+    toolbar.add_action("icon_action", icon_action, dummy_widget)
+    assert "icon_action" in toolbar.widgets
+    assert toolbar.widgets["icon_action"] == icon_action
+    assert icon_action.action in toolbar.actions()
+
+    # Add SeparatorAction
+    toolbar.add_action("separator_action", separator_action, dummy_widget)
+    assert "separator_action" in toolbar.widgets
+    assert toolbar.widgets["separator_action"] == separator_action
+
+    # Add MaterialIconAction
+    toolbar.add_action("material_icon_action", material_icon_action, dummy_widget)
+    assert "material_icon_action" in toolbar.widgets
+    assert toolbar.widgets["material_icon_action"] == material_icon_action
+    assert material_icon_action.action in toolbar.actions()
+
+
+def test_hide_show_action(toolbar_fixture, icon_action, qtbot, dummy_widget):
+    """Test hiding and showing actions on the toolbar."""
+    toolbar = toolbar_fixture
+
+    # Add an action
+    toolbar.add_action("icon_action", icon_action, dummy_widget)
+    assert icon_action.action.isVisible()
+
+    # Hide the action
+    toolbar.hide_action("icon_action")
+    qtbot.wait(100)
+    assert not icon_action.action.isVisible()
+
+    # Show the action
+    toolbar.show_action("icon_action")
+    qtbot.wait(100)
+    assert icon_action.action.isVisible()
+
+
+def test_add_duplicate_action(toolbar_fixture, icon_action, dummy_widget):
+    """Test that adding an action with a duplicate action_id raises a ValueError."""
+    toolbar = toolbar_fixture
+
+    # Add an action
+    toolbar.add_action("icon_action", icon_action, dummy_widget)
+    assert "icon_action" in toolbar.widgets
+
+    # Attempt to add another action with the same ID
+    with pytest.raises(ValueError) as excinfo:
+        toolbar.add_action("icon_action", icon_action, dummy_widget)
+    assert "Action with ID 'icon_action' already exists." in str(excinfo.value)
+
+
+def test_update_material_icon_colors(toolbar_fixture, material_icon_action, dummy_widget):
+    """Test updating the color of MaterialIconAction icons."""
+    toolbar = toolbar_fixture
+
+    # Add MaterialIconAction
+    toolbar.add_action("material_icon_action", material_icon_action, dummy_widget)
+    assert material_icon_action.action is not None
+
+    # Initial icon
+    initial_icon = material_icon_action.action.icon()
+
+    # Update color
+    new_color = "#ff0000"  # Red
+    toolbar.update_material_icon_colors(new_color)
+
+    # Updated icon
+    updated_icon = material_icon_action.action.icon()
+
+    # Assuming that the icon changes when color is updated
+    assert initial_icon != updated_icon
+
+
+def test_device_selection_action(toolbar_fixture, device_selection_action, dummy_widget):
+    """Test adding a DeviceSelectionAction to the toolbar."""
+    toolbar = toolbar_fixture
+    toolbar.add_action("device_selection", device_selection_action, dummy_widget)
+    assert "device_selection" in toolbar.widgets
+    # DeviceSelectionAction adds a QWidget, so it should be present in the toolbar's widgets
+    # Check if the widget is added
+    widget = device_selection_action.device_combobox.parentWidget()
+    assert widget in toolbar.findChildren(QWidget)
+    # Verify that the label is correct
+    label = widget.findChild(QLabel)
+    assert label.text() == "Select Device:"
+
+
+def test_widget_action(toolbar_fixture, widget_action, dummy_widget):
+    """Test adding a WidgetAction to the toolbar."""
+    toolbar = toolbar_fixture
+    toolbar.add_action("widget_action", widget_action, dummy_widget)
+    assert "widget_action" in toolbar.widgets
+    # WidgetAction adds a QWidget to the toolbar
+    container = widget_action.widget.parentWidget()
+    assert container in toolbar.findChildren(QWidget)
+    # Verify the label if present
+    label = container.findChild(QLabel)
+    assert label.text() == "Sample Label:"
+
+
+def test_expandable_menu_action(toolbar_fixture, expandable_menu_action, dummy_widget):
+    """Test adding an ExpandableMenuAction to the toolbar."""
+    toolbar = toolbar_fixture
+    toolbar.add_action("expandable_menu", expandable_menu_action, dummy_widget)
+    assert "expandable_menu" in toolbar.widgets
+    # ExpandableMenuAction adds a QToolButton with a QMenu
+    # Find the QToolButton
+    tool_buttons = toolbar.findChildren(QToolButton)
+    assert len(tool_buttons) > 0
+    button = tool_buttons[-1]  # Assuming it's the last one added
+    menu = button.menu()
+    assert menu is not None
+    # Check that menu has the correct actions
+    for action_id, sub_action in expandable_menu_action.actions.items():
+        # Check if a sub-action with the correct tooltip exists
+        matched = False
+        for menu_action in menu.actions():
+            if menu_action.toolTip() == sub_action.tooltip:
+                matched = True
+                break
+        assert matched, f"Sub-action with tooltip '{sub_action.tooltip}' not found in menu."
+
+
+def test_update_material_icon_colors_no_material_actions(toolbar_fixture, dummy_widget):
+    """Test updating material icon colors when there are no MaterialIconActions."""
+    toolbar = toolbar_fixture
+    # Ensure there are no MaterialIconActions
+    toolbar.update_material_icon_colors("#00ff00")
+
+
+def test_hide_action_nonexistent(toolbar_fixture):
+    """Test hiding an action that does not exist raises a ValueError."""
+    toolbar = toolbar_fixture
+    with pytest.raises(ValueError) as excinfo:
+        toolbar.hide_action("nonexistent_action")
+    assert "Action with ID 'nonexistent_action' does not exist." in str(excinfo.value)
+
+
+def test_show_action_nonexistent(toolbar_fixture):
+    """Test showing an action that does not exist raises a ValueError."""
+    toolbar = toolbar_fixture
+    with pytest.raises(ValueError) as excinfo:
+        toolbar.show_action("nonexistent_action")
+    assert "Action with ID 'nonexistent_action' does not exist." in str(excinfo.value)