Python Notes #3 - 1.21.2013

最新推荐文章于 2025-06-12 00:13:31 发布

CoreAlpha1900

最新推荐文章于 2025-06-12 00:13:31 发布

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分类专栏： PythonPython 文章标签： Note note

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本文探讨了Boehm曲线揭示的软件缺陷修复成本随时间增加而急剧上升的现象，并通过两个具体的单元测试案例展示了如何利用Python进行温度转换及冻结状态判断的功能测试。

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测试

Boehm Curve

[图片Boehm_Curve.jpg 来自我的Instagram]

你发现bug的时间越晚，修改它所需付出的代价也就越大，所以尽早捕获到bug将会降低总体时间。

1

# notes.py

'''Function for working with temperature.'''

def to_celsius(t):
    '''Convert Fahrenheit to Celsius.'''
    return round((t - 32.0) * 5.0 / 9.0)

def above_freezing(t):
    '''True if temperature in Celsius is above freezing, False otherwise.'''
    return t > 0

# test_notes.py

import nose
from notes import to_celsius
#from notes import above_freezing

def test_to_celsius():
    '''Test function for to_celsius'''
    assert to_celsius(100) == 37.8, 'Returning an unrounded result'
if __name__ == '__main__':
    nose.runmodule()

Python Shell:

[evaluate test_notes.py]
F
======================================================================
FAIL: Test function for to_celsius
----------------------------------------------------------------------
Traceback (most recent call last):
File "C:\Python27\lib\site-packages\nose-1.2.1-py2.7.egg\nose\case.py", line 197, in runTest
self.test(*self.arg)
File "<wingdb_compile>", line 9, in test_to_celsius
AssertionError: Returning an unrounded result

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (failures=1)
Traceback (most recent call last):
File "D:\Program Files\Wing IDE 101 4.1\src\debug\tserver\_sandbox.py", line 34, in <module>
File "C:\Python27\Lib\site-packages\nose-1.2.1-py2.7.egg\nose\core.py", line 292, in runmodule
main(defaultTest=name, **kw)
File "C:\Python27\Lib\site-packages\nose-1.2.1-py2.7.egg\nose\core.py", line 118, in __init__
**extra_args)
File "C:\Python27\Lib\unittest\main.py", line 95, in __init__
self.runTests()
File "C:\Python27\Lib\site-packages\nose-1.2.1-py2.7.egg\nose\core.py", line 200, in runTests
sys.exit(not self.success)
SystemExit: True

2

# test_notes.py

import nose
#from notes import to_celsius
from notes import above_freezing
def test_above_freezing():
    '''Test function for above_freezing.'''
    assert above_freezing(89.4), 'A temperature above freezing.'
    assert not above_freezing(-42), 'A temperature below freezing.'
    assert not above_freezing(0), 'A temperature at freezing.'

if __name__ == '__main__':
    nose.runmodule()

Python Shell:

[evaluate test_notes.py]
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK
Traceback (most recent call last):
File "D:\Program Files\Wing IDE 101 4.1\src\debug\tserver\_sandbox.py", line 34, in <module>
File "C:\Python27\Lib\site-packages\nose-1.2.1-py2.7.egg\nose\core.py", line 292, in runmodule
main(defaultTest=name, **kw)
File "C:\Python27\Lib\site-packages\nose-1.2.1-py2.7.egg\nose\core.py", line 118, in __init__
**extra_args)
File "C:\Python27\Lib\unittest\main.py", line 95, in __init__
self.runTests()
File "C:\Python27\Lib\site-packages\nose-1.2.1-py2.7.egg\nose\core.py", line 200, in runTests
sys.exit(not self.success)
SystemExit: False

有3条assert语句，但是Nose还是认为只运行了一个测试。对Nose而言，每个函数就是一个测试。

如果test_above_freezing中的第一个测试就失败了，我们将无法得到其他测试的任何信息。因此，

通常的做法是编写许多小的测试函数，分别测试少量的东西，而不是在其中放上一大堆各种各样的断言。