def test_get_layer_slice_fail(self):
     la = LayeredArray()
     with raises(IndexError):
         la.get_layer_slice(0)
 def test_get_layer_slice(self):
     la = LayeredArray()
     la.close_layer()
     layer_slice = la.get_layer_slice(0)
     assert layer_slice.start == 0
     assert layer_slice.stop == 0