':param sys_module: A ``sys`` like object whose ``argv``, ``stdout`` and
``stderr`` will be used in the script. Can be overridden in tests
to make assertions about the script argument parsing and output
printing. Default is ``sys``.'

def __init__(self, sys_module=None):

    if (sys_module is None):
        sys_module = sys
    self.sys_module = sys_module
