add comments and an extra testcase

Signed-off-by: Swapnil Wagh <waghswapnil@gmail.com>

imcsdk/imccoreutils.py

@@ -327,7 +327,7 @@ def extract_molist_from_method_response(method_response,
 
 
 def filter_molist_on_class_id(mo_list, class_id=None):
-    if class_id is None:
+    if not class_id:
         return mo_list
 
     out_list = [mo for mo in mo_list if mo._class_id.lower() == class_id.lower()]

imcsdk/imchandle.py

@@ -323,6 +323,11 @@ def query_children(self, in_mo=None, in_dn=None, class_id=None,
             parent_dn = in_dn
 
         meta_class_id = None
+        # Setting the default class-id to None
+        # When hierarchy and class-id are passed together to Cisco IMC,
+        # an empty response is received.
+        # Hence, passing the class-id only when hierarchy is not set
+        # When both hierarchy and class-id are set, do local filtering for class-id
         if class_id and not hierarchy:
             meta_class_id = imccoreutils.find_class_id_in_mo_meta_ignore_case(
                 class_id)

tests/common/test_query_children.py

@@ -38,6 +38,11 @@ def test_hierarchy():
     assert_equal(len(mos) > 30, True)
 
 
+def test_hierarchy_with_empty_class_id():
+    mos = handle.query_children(in_dn="sys/svc-ext", hierarchy=True, class_id="")
+    assert_equal(len(mos) > 30, True)
+
+
 def test_hierarchy_with_class_id():
     mos = handle.query_children(in_dn="sys/svc-ext", class_id="commSnmpUser",
                                 hierarchy=True)