def METHOD_NAME(self):
    # Check that special case handling of a vectorized string returning
    # function is taking place.
    def fn(coord, v):
        return "0123456789"[:v]
    with mock.patch(
        "numpy.vectorize", return_value=self.vectorised
    ) as vectorise_patch:
        with mock.patch("iris.coords.AuxCoord") as aux_coord_constructor:
            add_categorised_coord(
                self.cube, "foobar", self.coord, fn, units=self.units
            )
    self.assertEqual(
        aux_coord_constructor.call_args[0][0],
        vectorise_patch(fn, otypes=[object])(
            self.coord, self.coord.points
        ).astype("|S64"),
    )