def test_convert_bad_dimensions():
"""
Get Exception from converting to wrong dimensionality.
"""
u1 = Unit("Msun * Mpc**-2")
q1 = Quantity(1e-29, "g * cm**-3")
try:
q1.convert_to(u1)
except Exception:
pass
else:
assert False
def test_convert_to():
"""
Convert a density quantity from cgs to cosmological units.
"""
u1 = Unit("g * cm**-3")
u2 = Unit("Msun * Mpc**-3")
q1 = Quantity(1e-29, u1)
assert q1.units == u1
q1.convert_to(u2)
assert equal_sigfigs(q1.data, 1.47721e11, required_precision)
assert q1.units == u2
