'``DockerBuildScript.main`` raises ``SystemExit`` if there are missing
command line options.'

def test_usage_error_status(self):

    fake_sys_module = FakeSysModule(argv=[])
    script = DockerBuildScript(sys_module=fake_sys_module)
    exception = self.assertRaises(SystemExit, script.main)
    self.assertEqual(1, exception.code)
