sub_data = self.subscription.__dict__
         validate(instance=sub_data, schema=self.sub_schema)
         nf_filter = sub_data["nfFilter"]
-        for filter_name in nf_filter:
-            if len(nf_filter[filter_name]) > 0:
-                break
-        else:
+        if not [filter_name for filter_name, val in nf_filter.items() if len(val) > 0]:
             raise ValidationError("At least one filter within nfFilter must not be empty")
         logger.debug("Subscription schema is valid.")
 
 
         with self.assertRaises(ValidationError):
             self.app_conf.validate_sub_schema()
 
+    def test_utils_validate_config_subscription_nfFilter_not_empty(self):
+        self.app_conf.subscription.nfFilter = {
+            "nfNames": [
+
+            ],
+            "modelInvariantIDs": [
+
+            ],
+            "modelVersionIDs": [
+
+            ],
+            "modelNames": [
+
+            ]
+        }
+        with self.assertRaises(ValidationError):
+            self.app_conf.validate_sub_schema()
+
+    @patch('mod.logger.debug')
+    def test_utils_validate_config_subscription_nfFilter_with_empty_property(self, mock_logger):
+        self.app_conf.subscription.nfFilter = {
+            "nfNames": [
+                "^pnf.*",
+                "^vnf.*"
+            ],
+            "modelInvariantIDs": [
+                "7129e420-d396-4efb-af02-6b83499b12f8"
+            ],
+            "modelVersionIDs": [
+
+            ],
+            "modelNames": [
+                "pnf102"
+            ]
+        }
+        self.app_conf.validate_sub_schema()
+        mock_logger.assert_called_with("Subscription schema is valid.")
+
     def test_utils_validate_config_subscription_where_measurementTypes_is_empty(self):
         self.app_conf.subscription.measurementGroups = [{
             "measurementGroup": {