try:
...
except Exception1:
...
except Exception2:
...
finally:
...
如果在try中发生错误,那么except将捕获到指定错误,然后执行该段语句;而无论有无错误finally都会执行.
#-*-coding=utf-8-*- a = 0 try: 10 / a except BaseException: print(‘a is 0‘) finally: print(‘done‘)
所有异常的异常都继承自BaseExecption,所以可以指定BaseExecption来捕获所有异常
raise为编程者手动抛出错误
格式:
raise 错误类型(错误信息)
注意,raise语句如果不带参数，就会把当前错误原样抛出或抛出No active exception to reraise
#-*-coding=utf-8-*-
a = 0
try:
if a == 0:
raise ValueError(‘a is 0‘)
10 / a
except Exception as e:
print(e)
finally:
print(‘done‘)
assert a != 0, ‘a is 0‘
如果a不等于0,符合预期,否则输出a is 0
可以使用 -O来关闭assert输出:
python -O file.py
示例:
import logging logging.basicConfig(filename=‘log.log‘, level=logging.INFO) logging.info(‘发生错误‘)
self.assertEqual(abs(-1), 1) # 断言函数返回的结果与1相等
#断言是否会引发指定类型的错误
with self.assertRaises(KeyError):
value = d[‘empty‘]
if __name__ == ‘__main__‘:
unittest.main()
另一种方法是在命令行通过参数-m unittest直接运行单元测试,这样可以一次运行多个单元测试
import unittest
def say_hello():
return ‘hello‘
def division(a):
if a == 0:
raise ValueError(‘a不能为0‘)
return 100/a
class Test(unittest.TestCase):
def setUp(self):
print(‘测试开始了‘)
def test_say_hello(self):
self.assertEqual(say_hello(), ‘hello‘)
def test_division(self):
with self.assertRaises(ZeroDivisionError):
division(0)
def tearDown(self):
print(‘测试结束了‘)
if __name__ == ‘__main__‘:
unittest.main()
文档注释中写入交互命令,即可作为文档测试
class OK:
"""
this is test ok
Example:
>>> ok = OK()
>>> ok.my(1,2)
30
>>> ok.my(2,-1)
Traceback (most recent call last):
...
Param is error: -1
"""
def my(self, a, b):
return a + b
if __name__ == ‘__main__‘:
import doctest
doctest.testmod()
原文：https://www.cnblogs.com/itfenqing/p/10235774.html