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 1

You set maxDiff to None.

But you will have to actually use a unittest.TestCase for your tests for that to work. This should work.

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