def METHOD_NAME(self):
    '''Tests whether the slice_sets are deleted when the track() method
    of Drift is called
    '''
    beam = self.create_all1_bunch()
    beam._slice_sets = {'mock': 42}
    length = 0.2
    drift = Drift(self.alpha_array, length)
    drift.track(beam)
    self.assertFalse(beam._slice_sets, 'slice_sets not deleted after' +
                     'calling Drift.track() [changing the z-coordinates' +
                     ' of the beam]')