diff -r 6b07f261ccf4 Lib/unittest/case.py
--- a/Lib/unittest/case.py	Thu Sep 15 16:52:54 2016 -0400
+++ b/Lib/unittest/case.py	Thu Sep 15 14:40:05 2016 -0700
@@ -124,6 +124,11 @@
         return all(_is_subtype(e, basetype) for e in expected)
     return isinstance(expected, type) and issubclass(expected, basetype)
 
+def ensureNewline(line):
+    if line != '' and line[-1] != '\n':
+        line += '\n'
+    return line
+
 class _BaseTestCaseContext:
 
     def __init__(self, test_case):
@@ -1188,7 +1193,10 @@
                 firstlines = [first + '\n']
                 secondlines = [second + '\n']
             standardMsg = '%s != %s' % _common_shorten_repr(first, second)
-            diff = '\n' + ''.join(difflib.ndiff(firstlines, secondlines))
+            difflines = list(difflib.ndiff(firstlines, secondlines))
+            if len(difflines) > 1:
+                difflines = [ensureNewline(line) for line in difflines]
+            diff = '\n' + ''.join(difflines)
             standardMsg = self._truncateMessage(standardMsg, diff)
             self.fail(self._formatMessage(msg, standardMsg))