def test_Domain_cyclotomic_field():
K = ZZ.cyclotomic_field(12)
assert K.ext.minpoly == Poly(cyclotomic_poly(12))
assert K.dom == QQ
F = QQ.cyclotomic_field(3)
assert F.ext.minpoly == Poly(cyclotomic_poly(3))
assert F.dom == QQ
E = F.cyclotomic_field(4)
assert field_isomorphism(E.ext, K.ext) is not None
assert E.dom == QQ
