feat(colormap_button): colormap button with menu to select colormap filtered by the colormap type

tests/unit_tests/test_colormap_widget.py

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+import pytest
+from pyqtgraph.widgets.ColorMapButton import ColorMapButton
+
+from bec_widgets.widgets.colormap_widget.colormap_widget import BECColorMapWidget
+
+
+@pytest.fixture
+def color_map_widget(qtbot):
+    widget = BECColorMapWidget()
+    qtbot.addWidget(widget)
+    qtbot.waitExposed(widget)
+    yield widget
+
+
+def test_color_map_widget_init(color_map_widget):
+    """Test that the widget initializes correctly."""
+    assert color_map_widget is not None
+    assert isinstance(color_map_widget, BECColorMapWidget)
+    assert color_map_widget.colormap == "magma"
+    assert isinstance(color_map_widget.button, ColorMapButton)
+    # Check that the button has the correct initial colormap
+    assert color_map_widget.button.colorMap().name == "magma"
+
+
+def test_color_map_widget_set_valid_colormap(color_map_widget):
+    """
+    Test setting a valid colormap.
+    """
+    new_cmap = "viridis"
+    color_map_widget.colormap = new_cmap
+    assert color_map_widget.colormap == new_cmap
+    assert color_map_widget.button.colorMap().name == new_cmap
+
+
+def test_color_map_widget_set_invalid_colormap(color_map_widget):
+    """Test setting an invalid colormap."""
+    invalid_cmap = "invalid_colormap_name"
+    old_cmap = color_map_widget.colormap
+    color_map_widget.colormap = invalid_cmap
+    # Since invalid, the colormap should not change
+    assert color_map_widget.colormap == old_cmap
+    assert color_map_widget.button.colorMap().name == old_cmap
+
+
+def test_color_map_widget_signal_emitted(color_map_widget, qtbot):
+    """Test that the signal is emitted when the colormap changes."""
+    new_cmap = "plasma"
+    with qtbot.waitSignal(color_map_widget.colormap_changed_signal, timeout=1000) as blocker:
+        color_map_widget.colormap = new_cmap
+    assert blocker.signal_triggered
+    assert blocker.args == [new_cmap]
+    assert color_map_widget.colormap == new_cmap
+
+
+def test_color_map_widget_signal_not_emitted_for_invalid_colormap(color_map_widget, qtbot):
+    """Test that the signal is not emitted when an invalid colormap is set."""
+    invalid_cmap = "invalid_colormap_name"
+    with qtbot.assertNotEmitted(color_map_widget.colormap_changed_signal):
+        color_map_widget.colormap = invalid_cmap
+    # The colormap should remain unchanged
+    assert color_map_widget.colormap == "magma"
+
+
+def test_color_map_widget_resize(color_map_widget):
+    """Test that the widget resizes properly."""
+    width, height = 200, 50
+    color_map_widget.resize(width, height)
+    assert color_map_widget.width() == width
+    assert color_map_widget.height() == height