Fixes issue #2756.

Author: ycopin

astroquery/skyview/core.py

@@ -254,10 +254,10 @@ def get_image_list(self, position, survey, *, coordinates=None,
 
         if radius is not None:
             size_deg = str(radius.to(u.deg).value * 2)
-        elif width and height:
-            size_deg = "{0},{1}".format(width.to(u.deg).value,
-                                        height.to(u.deg).value)
-        elif width and height:
+        elif width is not None and height is not None:
+            size_deg = "{0},{1}".format(u.Quantity(width).to(u.deg).value,
+                                        u.Quantity(height).to(u.deg).value)
+        elif width is not None or height is not None:
             raise ValueError("Must specify width and height if you "
                              "specify either.")
         else:

astroquery/skyview/tests/test_skyview.py

@@ -83,3 +83,20 @@ def test_survey_validation(patch_get):
     assert str(ex.value) == ("Survey is not among the surveys hosted "
                              "at skyview.  See list_surveys or "
                              "survey_dict for valid surveys.")
+
+
+def test_get_image_list_size(patch_get, patch_fromname):
+    # Test with Quantities (as expected)
+    SkyView.get_image_list(position='Eta Carinae',
+                           survey='DSS',
+                           width=1 * u.deg, height=1 * u.deg)
+    with pytest.raises(u.UnitConversionError):
+        # Test with invalid Quantities
+        SkyView.get_image_list(position='Eta Carinae',
+                               survey='DSS',
+                               width=1, height='1 meter')
+    with pytest.raises(ValueError):
+        # Test with incomplete input
+        SkyView.get_image_list(position='Eta Carinae',
+                               survey='DSS',
+                               width=1 * u.deg, height=None)