Python:避免 NumPy 的 unittest.py 与本地 unittest.py 的冲突

有没有人遇到过这样的情况，他们将自己代码的单元测试写到一个名为unittest.py的文件中，发现它与NumPy的unittest.py模块冲突？换句话说，如果我将其写入本地目录中的 unittest.py:

if __name__ == "__main__": 
    print "pre-import" 
    #import numpy 
    print "post-import" 

然后(这里没有惊喜):

% python unittest.py 
pre-import 
post-import 

但如果我这样做:

if __name__ == "__main__": 
    print "pre-import" 
    import numpy 
    print "post-import" 

我得到:

% python unittest.py 
pre-import 
Traceback (most recent call last): 
  File "unittest.py", line 3, in <module> 
    import numpy 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/__init__.py", line 137, in <module> 
    import add_newdocs 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/add_newdocs.py", line 9, in <module> 
    from numpy.lib import add_newdoc 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/lib/__init__.py", line 4, in <module> 
    from type_check import * 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/lib/type_check.py", line 8, in <module> 
    import numpy.core.numeric as _nx 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/core/__init__.py", line 40, in <module> 
    from numpy.testing import Tester 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/testing/__init__.py", line 8, in <module> 
    from unittest import TestCase 
ImportError: cannot import name TestCase 

随后，iPython 加载失败:

% ipython 
WARNING: IPython History requires SQLite, your history will not be saved 
Traceback (most recent call last): 
  File "/home/jbbrown/local_bin/python/bin/ipython", line 7, in <module> 
    launch_new_instance() 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/frontend/terminal/ipapp.py", line 402, in launch_new_instance 
    app.initialize() 
  File "<string>", line 2, in initialize 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/config/application.py", line 84, in catch_config_error 
    return method(app, *args, **kwargs) 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/frontend/terminal/ipapp.py", line 312, in initialize 
    self.init_shell() 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/frontend/terminal/ipapp.py", line 332, in init_shell 
    ipython_dir=self.ipython_dir) 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/config/configurable.py", line 318, in instance 
    inst = cls(*args, **kwargs) 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/frontend/terminal/interactiveshell.py", line 183, in __init__ 
    user_module=user_module, custom_exceptions=custom_exceptions 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/core/interactiveshell.py", line 478, in __init__ 
    self.init_reload_doctest() 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/core/interactiveshell.py", line 662, in init_reload_doctest 
    doctest_reload() 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/IPython/utils/doctestreload.py", line 72, in doctest_reload 
    import doctest 
  File "/home/jbbrown/local_bin/python/lib/python2.7/doctest.py", line 2118, in <module> 
    class DocTestCase(unittest.TestCase): 
AttributeError: 'module' object has no attribute 'TestCase' 
 
If you suspect this is an IPython bug, please report it at: 
    https://github.com/ipython/ipython/issues 
or send an email to the mailing list at ipython-dev@scipy.org 
 
You can print a more detailed traceback right now with "%tb", or use "%debug" 
to interactively debug it. 
 
Extra-detailed tracebacks for bug-reporting purposes can be enabled via: 
    c.Application.verbose_crash=True 

有趣的是，如果我将 import 语句移到 "if __name__" 套件之外，例如，

print "pre-import" 
import numpy 
print "post-import" 
if __name__ == "__main__": 
    pass 

我得到:

% python unittest.py 
pre-import 
pre-import 
post-import 
Traceback (most recent call last): 
  File "unittest.py", line 2, in <module> 
    import numpy 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/__init__.py", line 137, in <module> 
    import add_newdocs 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/add_newdocs.py", line 9, in <module> 
    from numpy.lib import add_newdoc 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/lib/__init__.py", line 4, in <module> 
    from type_check import * 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/lib/type_check.py", line 8, in <module> 
    import numpy.core.numeric as _nx 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/core/__init__.py", line 40, in <module> 
    from numpy.testing import Tester 
  File "/home/jbbrown/local_bin/python/lib/python2.7/site-packages/numpy/testing/__init__.py", line 8, in <module> 
    from unittest import TestCase 
ImportError: cannot import name TestCase 

当然，更改包含我的单元测试的文件的名称并避免这种情况是微不足道的，但我想知道是否有其他人遇到过这种情况并想到了一种不包括重命名他们的单元测试文件的优雅解决方法？

请您参考如下方法:

您可以切换到absolute imports默认情况下，在 2.7 以上的 Python 版本上:

from __future__ import absolute_import 
 
if __name__ == "__main__": 
    print "pre-import" 
    import numpy 
    print "post-import"