crontest.py

def patch(f):
    def wrapper(*args, **kwargs):
        m = mock.mock_open()
        crontab_data = CrontabTest.cron_task
        m.return_value.read = lambda: crontab_data
        m.return_value.__iter__ = lambda s: s
        m.return_value.readlines = lambda: (l for l in CrontabTest.cron_task.split('\n'))
        def write_cmd(s):
            crontab_data = "%s%s" % (crontab_data, s)
        m.return_value.write = write_cmd
        with mock.patch("__builtin__.open", m, create=True):
            f(*args, m=m)
    return wrapper