关于python：assertRaises：在对方法进行单元测试时不会引发KeyError异常

assertRaises: KeyError exception is not raised while doing unit test of a method

我正在使用断言引发测试异常，即使引发异常，也不会由断言引发检测到异常。

测试方法如下：

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def process_data(data):
"""
process output data
:return: dict object
"""
component = dict()
try:
properties = dict()
properties['state'] = data['state']
properties['status'] = data['status']
component['properties'] = properties
except KeyError as e:
print"Missing key '{0}' in the response data".format(str(e))

return component

sample_data = {}
process_data(sample_data)

测试代码为：

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import unittest
import test_exception

class TestExceptions(unittest.TestCase):
"""
test class
"""
def test_process_data(self):
"""
test
:return:
"""
sample = {}
self.assertRaises(KeyError, test_exception.process_data, sample)

if __name__ == '__main__':
unittest.main()

但它没有按预期工作，出现以下错误：

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unittest -p test_test_exception.py
Missing key ''state'' in the response data

Missing key ''state'' in the response data

Failure
Traceback (most recent call last):
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/case.py", line 331, in run
testMethod()
File"/unittest/test_test_exception.py", line 16, in test_process_data
self.assertRaises(KeyError, test_exception.process_data, sample)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/case.py", line 475, in assertRaises
callableObj(*args, **kwargs)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/unittest/case.py", line 116, in __exit__
"{0} not raised".format(exc_name))
AssertionError: KeyError not raised

Ran 1 test in 0.001s

FAILED (failures=1)

Process finished with exit code 1

单元测试用例有什么问题？

感谢您用适当的上下文和代码发布一个清晰的问题。问题是：

1 2	except KeyError as e: print"Missing key '{0}' in the response data".format(str(e))

这应该是：

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except KeyError as e:
print"Missing key '{0}' in the response data".format(str(e))
raise

单元测试正在检查是否引发异常(代码完全短路)。查找异常类型并打印消息与使用raise关键字引发错误不同。