如何隐藏我的堆栈框架在TestCase子类中？

Question

我想将一个自定义断言方法添加到TestCase子类。我试图从unittest模块中复制我的实现，以便尽可能匹配常规TestCase的行为。 （我宁愿只是委托给self.assertEqual()，但这会导致更多的回溯噪音，请参阅下文）。unittest模块似乎在报告失败的断言时会自动隐藏其实施的一些内部细节。

import unittest 

class MyTestCase(unittest.TestCase): 
    def assertLengthIsOne(self, sequence, msg=None): 
     if len(sequence) != 1: 
      msg = self._formatMessage(msg, "length is not one") 
      raise self.failureException(msg) 

class TestFoo(MyTestCase): 
    seq = (1, 2, 3, 4, 5) 

    def test_stock_unittest_assertion(self): 
     self.assertEqual(len(self.seq), 1) 

    def test_custom_assertion(self): 
     self.assertLengthIsOne(self.seq) 


unittest.main() 

的这个输出是这样：

amoe@vuurvlieg $ python unittest-demo.py 
FF 
====================================================================== 
FAIL: test_custom_assertion (__main__.TestFoo) 
---------------------------------------------------------------------- 
Traceback (most recent call last): 
    File "unittest-demo.py", line 16, in test_custom_assertion 
    self.assertLengthIsOne(self.seq) 
    File "unittest-demo.py", line 7, in assertLengthIsOne 
    raise self.failureException(msg) 
AssertionError: length is not one 

====================================================================== 
FAIL: test_stock_unittest_assertion (__main__.TestFoo) 
---------------------------------------------------------------------- 
Traceback (most recent call last): 
    File "unittest-demo.py", line 13, in test_stock_unittest_assertion 
    self.assertEqual(len(self.seq), 1) 
AssertionError: 5 != 1 

---------------------------------------------------------------------- 
Ran 2 tests in 0.000s 

FAILED (failures=2) 

注意，定制的断言方法导致与两个框架，一个方法本身内的堆栈跟踪，而库存unittest方法仅具有一个框架，用户代码中的相关行。我怎样才能将这个框架隐藏行为应用于我自己的方法？

Answer 1

这个问题被回答了by Peter Otten on comp.lang.python。

将MyTestCase移动到单独的模块中，并定义一个全局变量__unittest = True。

$ cat mytestcase.py 
import unittest 

__unittest = True 

class MyTestCase(unittest.TestCase): 
    def assertLengthIsOne(self, sequence, msg=None): 
     if len(sequence) != 1: 
      msg = self._formatMessage(msg, "length is not one") 
      raise self.failureException(msg) 

$ cat mytestcase_demo.py 
import unittest 
from mytestcase import MyTestCase 

class TestFoo(MyTestCase): 
    seq = (1, 2, 3, 4, 5) 

    def test_stock_unittest_assertion(self): 
     self.assertEqual(len(self.seq), 1) 

    def test_custom_assertion(self): 
     self.assertLengthIsOne(self.seq) 

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

$ python mytestcase_demo.py 
FF 
====================================================================== 
FAIL: test_custom_assertion (__main__.TestFoo) 
---------------------------------------------------------------------- 
Traceback (most recent call last): 
    File "mytestcase_demo.py", line 11, in test_custom_assertion 
    self.assertLengthIsOne(self.seq) 
AssertionError: length is not one 

====================================================================== 
FAIL: test_stock_unittest_assertion (__main__.TestFoo) 
---------------------------------------------------------------------- 
Traceback (most recent call last): 
    File "mytestcase_demo.py", line 8, in test_stock_unittest_assertion 
    self.assertEqual(len(self.seq), 1) 
AssertionError: 5 != 1 

---------------------------------------------------------------------- 
Ran 2 tests in 0.000s 

FAILED (failures=2) 
$