def test_redshift_distance(kind):
"""Test :func:`astropy.cosmology.units.redshift_distance`."""
z = 15 * cu.redshift
d = getattr(Planck13, kind + "_distance")(z)
equivalency = cu.redshift_distance(cosmology=Planck13, kind=kind)
# properties of Equivalency
assert equivalency.name[0] == "redshift_distance"
assert equivalency.kwargs[0]["cosmology"] == Planck13
assert equivalency.kwargs[0]["distance"] == kind
# roundtrip
assert_quantity_allclose(z.to(u.Mpc, equivalency), d)
assert_quantity_allclose(d.to(cu.redshift, equivalency), z)
def test_redshift_distance_wrong_kind():
"""Test :func:`astropy.cosmology.units.redshift_distance` wrong kind."""
with pytest.raises(ValueError, match="`kind`"):
cu.redshift_distance(kind=None)