def METHOD_NAME(self):
    actions, angles, freqs = isochrone_xv_to_aa(
        self.w, self.potential
    )
    # Compare first element of orbit to genfunc, for speed
    x = self.w.xyz
    v = self.w.v_xyz
    m = self.potential.parameters["m"].value / 1e11
    b = self.potential.parameters["b"].value
    s_w = np.vstack((
        x[:, 0].to_value(u.kpc),
        v[:, 0].to_value(u.km / u.s)
    ))
    aa = np.array(
        [
            toy_potentials.angact_iso(s_w[:, i].T, params=(m, b))
            for i in range(s_w.shape[1])
        ]
    )
    s_actions = aa[:, :3] * u.km / u.s * u.kpc
    s_angles = aa[:, 3:] * u.rad
    assert u.allclose(actions[:, 0], s_actions.T, rtol=1e-8)
    assert_angles_allclose(angles[:, 0], s_angles.T, rtol=1e-8)
    # Test round-tripping
    if HAS_TWOBODY:
        # Check round-tripping for full orbits:
        w_rt = isochrone_aa_to_xv(actions, angles, self.potential)
        assert u.allclose(x, w_rt.xyz, atol=1E-10 * u.kpc)
        assert u.allclose(v, w_rt.v_xyz, atol=1E-10 * u.km/u.s)