From 5fe21ff91a0f3404680a7ff8c3c78b085b7ce92a Mon Sep 17 00:00:00 2001
From: Michael Foord <fuzzyman@voidspace.org.uk>
Date: Sat, 5 Jun 2010 13:38:16 +0000
Subject: [PATCH] unittest.TestCase assertion methods inform you when they have
 omitted an over long diff on failure. Issue 8351.

---
 Lib/unittest/case.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index ff6b8b3cb96..08e8c1e9640 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -14,6 +14,10 @@ from .util import (
 
 __unittest = True
 
+
+DIFF_OMITTED = ('\nDiff is %s characters long. '
+                 'Set self.maxDiff to None to see it.')
+
 class SkipTest(Exception):
     """
     Raise this exception in a test to skip it.
@@ -700,7 +704,7 @@ class TestCase(object):
         max_diff = self.maxDiff
         if max_diff is None or len(diff) <= max_diff:
             return message + diff
-        return message
+        return message + (DIFF_OMITTED % len(diff))
 
     def assertListEqual(self, list1, list2, msg=None):
         """A list-specific equality assertion.