Fix existing tests

Author: DomAyre

src/confcom/azext_confcom/custom.py

@@ -37,7 +37,7 @@ def acipolicygen_confcom(
     virtual_node_yaml_path: str,
     infrastructure_svn: str,
     tar_mapping_location: str,
-    container_definitions: list,
+    container_definitions: Optional[list] = None,
     approve_wildcards: str = False,
     outraw: bool = False,
     outraw_pretty_print: bool = False,
@@ -65,6 +65,9 @@ def acipolicygen_confcom(
             "For additional information, see http://aka.ms/clisecrets. \n",
         )
 
+    if container_definitions is None:
+        container_definitions = []
+
     stdio_enabled = resolve_stdio(enable_stdio, disable_stdio)
 
     if print_existing_policy and arm_template: