try:    #可能产生异常的代码块except Error1，Error2,... as e:    #处理异常的代码块1except Error3, Error4,... as e:    #处理异常的代码块2except Exception:    #处理其他异常

def test_raise():    with pytest.raises(ValueError,match='must be 0 or None'):        raise ValueError("value must be 0 or None")
def test_raise1():    with pytest.raises(ValueError) as exc_info:        raise ValueError("value must be 42")    assert exc_info.type is ValueError    assert exc_info.value.args[0] == "value must be 42"