Fix the unit tests by adding missing parameter

Without the fix, here is the test command and error:

nosetests -v -s tests

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ERROR: Failure: ImportError (No module named testsnosetests)
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Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/nose/loader.py", line 402, in loadTestsFromName
    module = resolve_name(addr.module)
  File "/Library/Python/2.7/site-packages/nose/util.py", line 311, in resolve_name
    module = __import__('.'.join(parts_copy))
ImportError: No module named testsnosetests

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