def METHOD_NAME(self):
    """Test the expand_bounds function fails if its effect would be
    to remove bounds from a bounded coordinate, i.e. if a mixture of
    bounded and unbounded coordinates are input"""
    self.cubelist[1].coord("time").bounds = None
    msg = "cannot expand bounds for a mixture of bounded / unbounded"
    with self.assertRaisesRegex(ValueError, msg):
        expand_bounds(self.cubelist[0], self.cubelist, ["time"])