test/infamy: handle empty NETCONF reply from remote

This patch handles a corner case we for some reason have not run into
yet.  With the new container operational data it was triggered almost
immediately, so let's add some basic guards around it and return None

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

test/infamy/netconf.py

@@ -246,10 +246,13 @@ class Device(object):
         data = NccGetDataReply(raw, ele)
         if(as_xml):
             return data
-        else:
-            # pylint: disable=c-extension-no-member
-            cfg = lxml.etree.tostring(data.data_ele[0])
-            return self.ly.parse_data_mem(cfg, "xml", parse_only=True)
+
+        if len(data.data_ele) == 0:
+            return None
+
+        # pylint: disable=c-extension-no-member
+        cfg = lxml.etree.tostring(data.data_ele[0])
+        return self.ly.parse_data_mem(cfg, "xml", parse_only=True)
 
     def get(self, xpath, as_xml=False):
         """RPC <get> (legacy NETCONF) fetches config:false data"""
@@ -259,15 +262,23 @@ class Device(object):
         """Return Python dictionary of <get> RPC data"""
         if(as_xml):
             return self.get(xpath, as_xml=True)
-        else:
-            return self.get(xpath).print_dict()
+
+        data = self.get(xpath)
+        if not data:
+            return None
+
+        return data.print_dict()
 
     def get_data(self, xpath=None, as_xml=False):
         """RPC <get-data> to fetch operational data"""
         if(as_xml):
             return self._get_data(xpath,as_xml)
-        else:
-            return self._get_data(xpath).print_dict()
+
+        data = self._get_data(xpath)
+        if not data:
+            return None
+
+        return data.print_dict()
 
     def get_config(self, xpath):
         return self._get(xpath, self.ncc.get_config)