diff -r ee074604bf0c Lib/unittest/case.py
--- a/Lib/unittest/case.py	Tue Feb 07 11:28:19 2017 +0300
+++ b/Lib/unittest/case.py	Wed Feb 08 09:30:48 2017 +0100
@@ -992,9 +992,10 @@ class TestCase(object):
                     differing += ('Unable to index element %d '
                                   'of second %s\n' % (len1, seq_type_name))
         standardMsg = differing
-        diffMsg = '\n' + '\n'.join(
-            difflib.ndiff(pprint.pformat(seq1).splitlines(),
-                          pprint.pformat(seq2).splitlines()))
+        diffMsg = difflib.unified_diff(pprint.pformat(seq1).splitlines(),
+                                       pprint.pformat(seq2).splitlines(),
+                                       lineterm='')
+        diffMsg = '\n' + '\n'.join(diffMsg)
 
         standardMsg = self._truncateMessage(standardMsg, diffMsg)
         msg = self._formatMessage(msg, standardMsg)
diff -r ee074604bf0c Lib/unittest/test/test_assertions.py
--- a/Lib/unittest/test/test_assertions.py	Tue Feb 07 11:28:19 2017 +0300
+++ b/Lib/unittest/test/test_assertions.py	Wed Feb 08 09:30:48 2017 +0100
@@ -240,8 +240,8 @@ class TestLongMessage(unittest.TestCase)
         # Error messages are multiline so not testing on full message
         # assertTupleEqual and assertListEqual delegate to this method
         self.assertMessages('assertSequenceEqual', ([], [None]),
-                            [r"\+ \[None\]$", "^oops$", r"\+ \[None\]$",
-                             r"\+ \[None\] : oops$"])
+                            [r"\+\[None\]$", "^oops$", r"\+\[None\]$",
+                             r"\+\[None\] : oops$"])
 
     def testAssertSetEqual(self):
         self.assertMessages('assertSetEqual', (set(), set([None])),
diff -r ee074604bf0c Lib/unittest/test/test_case.py
--- a/Lib/unittest/test/test_case.py	Tue Feb 07 11:28:19 2017 +0300
+++ b/Lib/unittest/test/test_case.py	Wed Feb 08 09:30:48 2017 +0100
@@ -775,8 +775,10 @@ class Test_TestCase(unittest.TestCase, T
         self.assertEqual(self.maxDiff, 80*8)
         seq1 = 'a' + 'x' * 80**2
         seq2 = 'b' + 'x' * 80**2
-        diff = '\n'.join(difflib.ndiff(pprint.pformat(seq1).splitlines(),
-                                       pprint.pformat(seq2).splitlines()))
+        diff = difflib.unified_diff(pprint.pformat(seq1).splitlines(),
+                                    pprint.pformat(seq2).splitlines(),
+                                    lineterm='')
+        diff = '\n'.join(diff)
         # the +1 is the leading \n added by assertSequenceEqual
         omitted = unittest.case.DIFF_OMITTED % (len(diff) + 1,)