test: make fake args copyable

Change-Id: I2cb6efff611032ff4b0a20258ed8ced0aaa3a958
Reviewed-on: http://gerrit.aldebaran.lan/45552
Reviewed-by: dmerejkowsky <dmerejkowsky@aldebaran-robotics.com>
Tested-by: dmerejkowsky <dmerejkowsky@aldebaran-robotics.com>