1.1   单元测试

1.1.1   单元测试编写

单元测试是用来对一个模块、一个函数或者一个类来进行正确性检验的测试工作。

编写一个Dict类,这个类的行为和dict一致,但是通过属性来访问。

>>> d = Dict(a=1, b=2)

>>> d['a']

1

>>> d.a

1

class dict编写如下:

[root@daidai python]# cat mydict.py

#!/usr/bin/python

# -*- coding:utf-8 -*-

 

class Dict(dict):

   def __init__(self, **kw):

       super().__init__(**kw)

   def __getattr__(self, key):

       try:

           return self[key]

       except KeyError:

           raise AttributeError(r"'Dict' has no attribute %s." % key)

   def __setattr__(self, key, value):

       self[key] = value

编写单元测试:

[root@daidai python]# cat mydict_test.py

#!/usr/bin/python

# -*- coding:utf-8 -*-

 

import unittest

from mydict import Dict

class TestDict(unittest.TestCase):     #测试类从unittest.TestCase继承

   def test_init(self):            #不是test开头的方法不被执行

       d = Dict(a = 1, b = 'test')

       self.assertEqual(d.a, 1)

       self.assertEqual(d.b, 'test')

       self.assertTrue(isinstance(d, dict))

   def test_key(self):

       d = Dict()

       d['key'] = 'value'

       self.assertEqual(d.key, 'value')

   def test_attr(self):

       d = Dict()

       d.key = 'value'

       self.assertTrue('key' in d)

       self.assertEqual(d['key'], 'value')

   def test_keyerror(self):

       d = Dict()

       with self.assertRaises(KeyError):  #通过d['empty']访问不存在的key时,断言会抛出KeyError

           value = d['empty']

   def test_attrerror(self):

       d = Dict()

        with self.assertRaises(AttributeError): #通过d.empty访问不存在的key时,我们期待抛出AttributeError

           value = d.empty

 

if __name__ == '__main__':

unittest.main()     #运行单元测试

1.1.2   运行单元测试

[root@daidai python]# python mydict_test.py #加上unittest.main()运行语句

.....

----------------------------------------------------------------------

Ran 5 tests in 0.001s

 

OK

[root@daidai python]#

[root@daidai python]#

[root@daidai python]# python -m unittest mydict_test  #不用加上unittest.main()运行语句

.....

----------------------------------------------------------------------

Ran 5 tests in 0.001s

 

OK

1.1.3   setUp() & tearDown()

这两个方法分别在单元测试中每个测试方法的前后被执行。

[root@daidai python]# cat mydict_test.py

#!/usr/bin/python

# -*- coding:utf-8 -*-

 

import unittest

from mydict import Dict

class TestDict(unittest.TestCase):

    def setUp(self):

        print('test begins...')

   def test_init(self):

       d = Dict(a = 1, b = 'test')

       self.assertEqual(d.a, 1)

       self.assertEqual(d.b, 'test')

       self.assertTrue(isinstance(d, dict))

   def test_key(self):

       d = Dict()

       d['key'] = 'value'

       self.assertEqual(d.key, 'value')

   def test_attr(self):

       d = Dict()

       d.key = 'value'

       self.assertTrue('key' in d)

       self.assertEqual(d['key'], 'value')

   def test_keyerror(self):

       d = Dict()

       with self.assertRaises(KeyError):

           value = d['empty']

   def test_attrerror(self):

       d = Dict()

       with self.assertRaises(AttributeError):

           value = d.empty

    def tearDown(self):

        print('test ends...')

 

#if __name__ == '__main__':

#   unittest.main()

[root@daidai python]# pythonmydict_test.py    #发现这样测试没有作用

[root@daidai python]# python -m unittestmydict_test

test begins...

test ends...

.test begins...

test ends...

.test begins...

test ends...

.test begins...

test ends...

.test begins...

test ends...

.

----------------------------------------------------------------------

Ran 5 tests in 0.001s

 

OK

1.2   文档测试

当我们编写注释时,如果写上这样的注释:

 

def abs(n):

   '''

   Function to get absolute value of number.

 

   Example:

 

   >>> abs(1)

    1

   >>> abs(-1)

    1

   >>> abs(0)

    0

   '''

   return n if n >= 0 else (-n)

无疑更明确地告诉函数的调用者该函数的期望输入和输出。

 

并且,Python内置的“文档测试”(doctest)模块可以直接提取注释中的代码并执行测试。

 

doctest严格按照Python交互式命令行的输入和输出来判断测试结果是否正确。只有测试异常的时候,可以用...表示中间一大段烦人的输出。

 

让我们用doctest来测试上次编写的Dict类:

 

# mydict2.py

class Dict(dict):

   '''

   Simple dict but also support access as x.y style.

 

   >>> d1 = Dict()

   >>> d1['x'] = 100

   >>> d1.x

   100

   >>> d1.y = 200

   >>> d1['y']

   200

   >>> d2 = Dict(a=1, b=2, c='3')

   >>> d2.c

   '3'

   >>> d2['empty']

   Traceback (most recent call last):

       ...

   KeyError: 'empty'

   >>> d2.empty

   Traceback (most recent call last):

       ...

   AttributeError: 'Dict' object has no attribute 'empty'

   '''

   def __init__(self, **kw):

       super(Dict, self).__init__(**kw)

 

   def __getattr__(self, key):

       try:

           return self[key]

       except KeyError:

           raise AttributeError(r"'Dict' object has no attribute '%s'" %key)

 

   def __setattr__(self, key, value):

       self[key] = value

 

if __name__=='__main__':

   import doctest

   doctest.testmod()

运行python3 mydict2.py

 

$ python3 mydict2.py

什么输出也没有。这说明我们编写的doctest运行都是正确的。如果程序有问题,比如把__getattr__()方法注释掉,再运行就会报错:

 

$ python3 mydict2.py

**********************************************************************

File "/Users/michael/Github/learn-python3/samples/debug/mydict2.py",line 10, in __main__.Dict

Failed example:

   d1.x

Exception raised:

   Traceback (most recent call last):

     ...

   AttributeError: 'Dict' object has no attribute 'x'

**********************************************************************

File"/Users/michael/Github/learn-python3/samples/debug/mydict2.py", line16, in __main__.Dict

Failed example:

   d2.c

Exception raised:

   Traceback (most recent call last):

     ...

   AttributeError: 'Dict' object has no attribute 'c'

**********************************************************************

1 items had failures:

   2of   9 in __main__.Dict

***Test Failed*** 2 failures.

注意到最后3行代码。当模块正常导入时,doctest不会被执行。只有在命令行直接运行时,才执行doctest。所以,不必担心doctest会在非测试环境下执行。