'Replace existing column with a new column'

def test_replace_column(self, table_types):

    self._setup(table_types)
    t = table_types.Table([self.a, self.b])
    ta = t['a']
    tb = t['b']
    vals = [1.2, 3.4, 5.6]
    for col in (vals, table_types.Column(vals), table_types.Column(vals, name='a'), table_types.Column(vals, name='b')):
        t.replace_column('a', col)
        assert np.all((t['a'] == vals))
        assert (t['a'] is not ta)
        assert (t['b'] is tb)
        assert (t.colnames == ['a', 'b'])
        assert (t['a'].meta == {})
        assert (t['a'].format is None)
