def test_polymatrix_rref():
M = PolyMatrix([[1, 2], [3, 4]], x)
assert M.rref() == (PolyMatrix.eye(2, x), (0, 1))
raises(ValueError, lambda: PolyMatrix([1, 2], ring=ZZ[x]).rref())
raises(ValueError, lambda: PolyMatrix([1, x], ring=QQ[x]).rref())
def test_polymatrix_ones_zeros():
assert PolyMatrix.zeros(1, 2, x) == PolyMatrix([[0, 0]], x)
assert PolyMatrix.eye(2, x) == PolyMatrix([[1, 0], [0, 1]], x)