def METHOD_NAME(self, mock_os_sys):
    global os_system_calls, os_system_call_index
    mock_os_sys.side_effect = mock_os_system_call
    for entry in test_data:
        if entry["cmd"]:
            os_system_calls.append({"cmd": entry["cmd"], "rc": 0 })
        msg = "case failed: {}".format(str(entry))
        vlan_validator(entry["old"], entry["upd"], None)
    # Test failure case
    #
    os_system_calls = test_rsyslog_fail
    os_system_call_index = 0
    rc = rsyslog_validator("", "", "")
    assert not rc, "rsyslog_validator expected to fail"
    os_system_calls = []
    os_system_call_index = 0
    for entry in test_vlanintf_data:
        if entry["cmd"]:
            os_system_calls.append({"cmd": entry["cmd"], "rc": 0 })
        msg = "case failed: {}".format(str(entry))
        vlanintf_validator(entry["old"], entry["upd"], None)