How to print the 2 full objects instead of show diff on a python unit test error?

Question

For example, if I run this test:

import unittest

class TestAssertEqual(unittest.TestCase):
    def testString(self):
        self.maxDiff = None
        a = u'looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggloooooooo\nooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg'
        b = u'looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggg\nggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnn\nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg'
        self.assertEqual(a, b)

if __name__ == '__main__':
    unittest.main()

I can barely understand nothing when the multi line diff is show:

F
======================================================================
FAIL: testString (__main__.TestAssertEqual)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\User\Downloads\test.py", line 8, in testString
    self.assertEqual(a, b)
AssertionError: u'looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnn [truncated]... != u'looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnn [truncated]...
+ looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggg
+ ggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnn
- looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggloooooooo
?                                                                                                                                                                                               -----------
+ nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg? +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
- ooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg

----------------------------------------------------------------------
Ran 1 test in 0.006s

FAILED (failures=1)

Is it possible to python to only show the strings instead of doing a multi line diff? For example:

F
======================================================================
FAIL: testString (__main__.TestAssertEqual)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\User\Downloads\test.py", line 8, in testString
    self.assertEqual(a, b)
AssertionError: 
looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggloooooooo
ooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg                                                                                                                                             
!=
looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggg
ggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnn
nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg

----------------------------------------------------------------------
Ran 1 test in 0.006s

FAILED (failures=1)

---

While searching I found on the question Comparison of multi-line strings in Python unit test where they explained that several types are registered to be showed on the diff mode. These are the types:

self.addTypeEqualityFunc(dict, 'assertDictEqual')
self.addTypeEqualityFunc(list, 'assertListEqual')
self.addTypeEqualityFunc(tuple, 'assertTupleEqual')
self.addTypeEqualityFunc(set, 'assertSetEqual')
self.addTypeEqualityFunc(frozenset, 'assertSetEqual')
try:
    self.addTypeEqualityFunc(unicode, 'assertMultiLineEqual')
except NameError:
    # No unicode support in this build
    pass

As we may see, the unicode are registered, that is way they where displayed as diff on the minimal example just above. However, there are other types which are not registered and will not render the diff mode, like the str type.

1. Can I unregister all these types so nothing is displayed on diff mode?

2. Could the output format type to be displayed on the format:

   AssertionError: 
   'a'
   !=
   'b'
   
   ----------------------------------------------------------------------
   Ran 1 test in 0.006s
   

   Instead of:

   AssertionError: 'b' != 'a'
   
   ----------------------------------------------------------------------
   Ran 1 test in 0.001s
   

Answer 1

Using the code on this answer at How to wrap correctly the unit testing diff with diffMode=0 as characters seems to produce better result than the built-in python unittest module behavior:

  looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg
+ looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggg
+ gggggggggggggggggggg  gl
+ o  oooooooo
+ oooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnn
+ nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggloooooooo  ooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
- g  ggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg

Anyways, you can do a side by side diff with the following:

import unittest

class TestRules(unittest.TestCase):
    ## Set the maximum size of the assertion error message when Unit Test fail
    maxDiff = None

    def setUp(self):
        self.addTypeEqualityFunc(str, self.myAssertEquals)

    def myAssertEquals(self, expected, actual, msg=""):

        if expected != actual:
            self.fail( '\n%s\n!=\n%s' % ( expected, actual ) )

    def test_badWrapping(self):
        a = u'looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggloooooooo\nooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg'
        b = u'looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggg\nggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnn\nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg'

        self.myAssertEquals(
            a
            ,
            b
        )

unittest.main(failfast=True)

Resulting in the following output as desired:

F
======================================================================
FAIL: test_badWrapping (__main__.TestRules)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\User\Downloads\test.py", line 23, in test_badWrapping
    b
  File "D:\User\Downloads\test.py", line 14, in myAssertEquals
    self.fail( '\n%s\n!=\n%s' % ( expected, actual ) )
AssertionError: 
looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggloooooooo
ooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg
!=
looooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnngggggggggggggggggggggggggggggggggggggggggggggggg
ggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnn
nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggglooooooooooooooooooooooooooooooooooooooooooooooooooooonnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg

----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (failures=1)