How to output full diffs in Django unit tests?

Question

When I use assertEqual() with two dictionaries in REPL, it shows me a diff, e.g.:

>>> import unittest
>>> class A(unittest.TestCase):
...   pass
... 
>>> a = A()
>>> d1 = dict(zip(range(10), range(1000000, 1000010)))
>>> d2 = dict(zip(range(3, 13), range(1000003, 1000013)))
>>> a.assertEqual(d1, d2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.5/unittest/case.py", line 820, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/usr/lib/python3.5/unittest/case.py", line 1111, in assertDictEqual
    self.fail(self._formatMessage(msg, standardMsg))
  File "/usr/lib/python3.5/unittest/case.py", line 665, in fail
    raise self.failureException(msg)
AssertionError: {0: 1000000, 1: 1000001, 2: 1000002, 3: 10[73 chars]0009} != {3: 1000003, 4: 1000004, 5: 1000005, 6: 10[76 chars]0012}
- {0: 1000000,
-  1: 1000001,
-  2: 1000002,
-  3: 1000003,
? ^

+ {3: 1000003,
? ^

   4: 1000004,
   5: 1000005,
   6: 1000006,
   7: 1000007,
   8: 1000008,
-  9: 1000009}
?            ^

+  9: 1000009,
?            ^

+  10: 1000010,
+  11: 1000011,
+  12: 1000012}

When I do the same in a Django unit test, sometimes it prints a diff and sometimes only the first shortened line. I wonder, how can I make it always print the diff.
I run Django tests with ./manage.py test -v 3.

Answer 1

If you set maxDiff to None, then the full diff will be shown.

class A(unittest.TestCase):
    maxDiff = None
    ...