Python Notes #3 - 1.21.2013

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.pyimport nosefrom notes import to_celsius#from notes import above_freezingdef 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.pyimport nose#from notes import to_celsiusfrom notes import above_freezingdef 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。