def METHOD_NAME(self):
    """
    Test from dark slit image to bright slit image (gray)
    """
    bl = self.light
    ccd = mock.FakeCCD(self.img_spccd_loff)
    f = turnOnLight(bl, ccd)
    time.sleep(1)  # > exposureTime (=0.1 s)
    self.assertFalse(f.done())
    logging.debug("changing image")
    # simulate light turning on
    ccd.fake_img = self.img_spccd_lon
    time.sleep(1)
    self.assertTrue(f.done())
    f.result()