Problems of integration

Why is integration of Django testing with other tools even an issue? Consider the case of wanting to use the nose test framework. It provides its own command, nosetests, to find and run tests in a project tree. However, attempting to run nosetests, instead of manage.py test, in a Django project tree quickly reveals a problem:

kmt@lbox:/dj_projects/marketr$ nosetests 
E 
====================================================================== 
ERROR: Failure: ImportError (Settings cannot be imported, because environment variable DJANGO_SETTINGS_MODULE is undefined.) 
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Traceback (most recent call last): 
  File "/usr/lib/python2.5/site-packages/nose-0.11.1-py2.5.egg/nose/loader.py", line 379, in loadTestsFromName 
    addr.filename, addr.module) 
  File "/usr/lib/python2.5/site-packages/nose-0.11.1-py2.5.egg/nose/importer.py", line 39, in importFromPath 
    return self.importFromDir(dir_path, fqname...