Merge pull request #2342 from jrbaez01/issue/#2341-accept-one-default-argument

#2341: Accept default argument value when args lenght equal 1

flask/cli.py

@@ -87,12 +87,15 @@ def call_factory(app_factory, script_info, arguments=()):
     of arguments. Checks for the existence of a script_info argument and calls
     the app_factory depending on that and the arguments provided.
     """
-    arg_names = getargspec(app_factory).args
+    args_spec = getargspec(app_factory)
+    arg_names = args_spec.args
+    arg_defaults = args_spec.defaults
+
     if 'script_info' in arg_names:
         return app_factory(*arguments, script_info=script_info)
     elif arguments:
         return app_factory(*arguments)
-    elif not arguments and len(arg_names) == 1:
+    elif not arguments and len(arg_names) == 1 and arg_defaults is None:
         return app_factory(script_info)
     return app_factory()