def METHOD_NAME(self):
    # We should still get a good solution, as we should be
    # approximating the gradient automatically.
    op = OptProblemNoGrad()
    conditions = {"xtol_rel": 1e-6, "max_eval": 100}
    result = op.optimise(
        np.array([1, 1]), algorithm="SLSQP", opt_conditions=conditions
    )
    np.testing.assert_allclose(result.x, [1 / 3, 8 / 27], rtol=1e-4)