assertEqual doesn't display newline differences quite well

Lib/unittest/test/test_case.py

--- a/Lib/unittest/test/test_case.py	Sat Jun 25 15:03:52 2011 +0200
+++ b/Lib/unittest/test/test_case.py	Sun Jun 26 17:12:16 2011 +0200
@@ -756,6 +756,16 @@
         self.assertEqual(str(cm.exception), '%r != %r' % (s1, s2))
         self.assertEqual(s + 'a', s + 'a')
 
+    def testAssertEqualHumanReadableOutput(self):
+        # Issue #12038: Make the assertion error message more human redable
+        # for long strings.
+        s1 = "aaaaaa"
+        s2 = "abbbbb"
+        with self.assertRaises(self.failureException) as cm:
+            self.assertEqual(s1, s2)
+        self.assertIn("aa [truncated]... != 'ab [truncated]...",
+                      str(cm.exception))
+
     def testAssertCountEqual(self):
         a = object()
         self.assertCountEqual([1, 2, 3], [3, 2, 1])