How to set self.maxDiff in nose to get full diff output?
Question: When using nose 1.2.1 with Python 3.3.0, I sometimes get an error message
similar to the following one

    
    
    ======================================================================
    FAIL: maxdiff2.test_equal
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "/usr/local/lib/python3.3/site-packages/nose/case.py", line 198, in runTest
        self.test(*self.arg)
      File "/Users/loic/cmrsj/Calculus_II/scrap/maxdiff2.py", line 32, in test_equal
        assert_equal(str1, str2)
    AssertionError: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec a
    diam lectus.\n [truncated]... != 'Suspendisse lectus leo, consectetur in tempor sit
    amet, placerat quis neque.\nE [truncated]...
    Diff is 1780 characters long. Set self.maxDiff to None to see it.
    
    ----------------------------------------------------------------------
    Ran 1 test in 0.064s
    
    FAILED (failures=1)
    

In many situations, to figure out what the error really is, I need to see the
full diff output. However, I have no idea of how to set that `self.maxDiff`.
Googling for nose and maxDiff does not help. With the same version of nose on
Python 2.7.1 the full diff is printed to screen.

Here is a simple script that generates the error above when run with
`nosetests-3.3`:

    
    
    from nose.tools import assert_equal
    
    def test_equal():
        str1 = """\
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec a diam lectus.
    Sed sit amet ipsum mauris. Maecenas congue ligula ac quam viverra nec
    consectetur ante hendrerit. Donec et mollis dolor. Praesent et diam eget libero
    egestas mattis sit amet vitae augue. Nam tincidunt congue enim, ut porta lorem
    lacinia consectetur. Donec ut libero sed arcu vehicula ultricies a non tortor.
    Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean ut gravida
    lorem. Ut turpis felis, pulvinar a semper sed, adipiscing id dolor.
    Pellentesque auctor nisi id magna consequat sagittis. Curabitur dapibus enim
    sit amet elit pharetra tincidunt feugiat nisl imperdiet. Ut convallis libero in
    urna ultrices accumsan. Donec sed odio eros. Donec viverra mi quis quam
    pulvinar at malesuada arcu rhoncus. Cum sociis natoque penatibus et magnis dis
    parturient montes, nascetur ridiculus mus. In rutrum accumsan ultricies. Mauris
    vitae nisi at sem facilisis semper ac in est."""
    
        str2 = """\
    Suspendisse lectus leo, consectetur in tempor sit amet, placerat quis neque.
    Etiam luctus porttitor lorem, sed suscipit est rutrum non. Curabitur lobortis
    nisl a enim congue semper. Aenean commodo ultrices imperdiet. Vestibulum ut
    justo vel sapien venenatis tincidunt. Phasellus eget dolor sit amet ipsum
    dapibus condimentum vitae quis lectus. Aliquam ut massa in turpis dapibus
    convallis. Praesent elit lacus, vestibulum at malesuada et, ornare et est. Ut
    augue nunc, sodales ut euismod non, adipiscing vitae orci. Mauris ut placerat
    justo. Mauris in ultricies enim. Quisque nec est eleifend nulla ultrices
    egestas quis ut quam. Donec sollicitudin lectus a mauris pulvinar id aliquam
    urna cursus. Cras quis ligula sem, vel elementum mi. Phasellus non ullamcorper
    urna."""
    
        assert_equal(str1, str2)
    


Answer: You set `maxDiff` to `None`.

But you will have to actually use a
[`unittest.TestCase`](http://docs.python.org/2/library/unittest.html#unittest.TestCase.maxDiff)
for your tests for that to work.This shold work.

    
    
    class MyTest(unittest.TestCase):
    
        maxDiff = None
    
        def test_diff(self):
              <your test here>
    

