data-menu: handle associated data layer logic (#3370)

* logic to connect visibilities of child/parent layers from data-menu
* test coverage

CHANGES.rst

@@ -4,7 +4,7 @@
 New Features
 ------------
 
-- New design for viewer legend and data-menu. [#3220, #3254, #3263, #3264, #3271, #3272, #3274, #3289, #3310]
+- New design for viewer legend and future data-menu. [#3220, #3254, #3263, #3264, #3271, #3272, #3274, #3289, #3310, #3370]
 
 - Improve performance while importing multiple regions. [#3321]
 

jdaviz/configs/default/plugins/data_menu/data_menu.py

@@ -358,6 +358,15 @@ def set_layer_visibility(self, layer_label, visible=True):
                 layer.visible = visible
             elif hasattr(layer.layer, 'data') and layer.layer.data.label == layer_label:
                 layer.visible = layer.layer.label in self.visible_layers
+            if not visible and self.app._get_assoc_data_parent(layer.layer.label) == layer_label:
+                # then this is a child-layer of a parent-layer that is being hidden
+                # so also hide the child-layer
+                layer.visible = False
+
+        if visible and (parent_label := self.app._get_assoc_data_parent(layer_label)):
+            # ensure the parent layer is also visible
+            self.set_layer_visibility(parent_label, visible=True)
+
         return self.visible_layers
 
     def toggle_layer_visibility(self, layer_label):

jdaviz/configs/default/tests/test_data_menu.py

@@ -1,3 +1,4 @@
+from astropy.io import fits
 import pytest
 import numpy as np
 from specutils import SpectralRegion
@@ -146,6 +147,33 @@ def test_data_menu_remove_subset(specviz_helper, spectrum1d):
     # assert dm.layer.choices == ['test', 'test2', 'Subset 2']
 
 
+def test_data_menu_dq_layers(imviz_helper):
+    hdu_data = fits.ImageHDU(np.zeros(shape=(2, 2)))
+    hdu_data.name = 'SCI'
+    hdu_dq = fits.ImageHDU(np.zeros(shape=(2, 2), dtype=np.int32))
+    hdu_dq.name = 'DQ'
+    data = fits.HDUList([fits.PrimaryHDU(), hdu_data, hdu_dq])
+
+    imviz_helper.load_data(data, data_label="image", ext=('SCI', 'DQ'), show_in_viewer=True)
+
+    dm = imviz_helper.viewers['imviz-0']._obj.data_menu
+    assert dm.layer.choices == ['image[DQ,1]', 'image[SCI,1]']
+    assert len(dm._obj.visible_layers) == 2
+
+    # turning off image (parent) data-layer should also turn off DQ
+    dm.set_layer_visibility('image[SCI,1]', False)
+    assert len(dm._obj.visible_layers) == 0
+
+    # turning on image (parent) should leave DQ off
+    dm.set_layer_visibility('image[SCI,1]', True)
+    assert len(dm._obj.visible_layers) == 1
+
+    # turning on DQ (child, when parent off) should show parent
+    dm.set_layer_visibility('image[SCI,1]', False)
+    dm.set_layer_visibility('image[DQ,1]', True)
+    assert len(dm._obj.visible_layers) == 2
+
+
 @pytest.mark.skip(reason="known issue")
 def test_data_menu_subset_appearance(specviz_helper, spectrum1d):
     # NOTE: this test is similar to above - the subset is appearing in time IF there