'Test illegal database merger.'

def test_illegal_merge(self):

    with pytest.raises(VOSError):
        new_db = self.db.merge(u'not_a_db')
    other_db = vos_catalog.VOSDatabase.create_empty()
    other_db[u'__version__'] = 99
    with pytest.raises(VOSError):
        new_db = self.db.merge(other_db)
