adding test for DAGSets explicitly

test/test_basic.py

@@ -331,26 +331,28 @@ def test_area(request):
 def test_add_groups(request):
     test_file = str(request.path.parent / 'fuel_pin.h5m')
     model = dagmc.DAGModel(test_file)
+    volumes = model.volumes
+    surfaces = model.surfaces
 
     for group in model.groups.values():
         group.delete()
 
     assert len(model.groups) == 0
 
     group_map = {("mat:fuel", 1): [1, 2],
-                 ("mat:Graveyard", 0): [6],
+                 ("mat:Graveyard", 0): [volumes[6]],
                  ("mat:41", 2): [3],
-                 ("boundary:Reflecting", 3): [27, 28, 29]
+                 ("boundary:Reflecting", 3): [27, 28, 29],
+                 ("boundary:Vacuum", 4): [surfaces[24], surfaces[25]]
                  }
 
     model.add_groups(group_map)
 
     groups = model.groups
-    volumes = model.volumes
-    surfaces = model.surfaces
 
-    assert len(groups) == 4
+    assert len(groups) == 5
     assert [1, 2] == sorted(groups['mat:fuel'].get_volume_ids())
     assert [6] == groups['mat:Graveyard'].get_volume_ids()
     assert [3] == groups['mat:41'].get_volume_ids()
     assert [27, 28, 29] == sorted(groups['boundary:Reflecting'].get_surface_ids())
+    assert [24, 25] == sorted(groups['boundary:Vacuum'].get_surface_ids())