'Raise exception when trying to replace column via table.columns object'

def test_fail_replace_column(self, table_types):

    self._setup(table_types)
    t = table_types.Table([self.a, self.b])
    with pytest.raises(ValueError):
        t.columns['a'] = [1, 2, 3]
    with pytest.raises(ValueError):
        t.replace_column('not    there', [1, 2, 3])
