diff -r 2b4b475f2ed3 Lib/test/test_csv.py
--- a/Lib/test/test_csv.py	Sat Dec 13 16:13:24 2014 -0500
+++ b/Lib/test/test_csv.py	Sun Dec 14 11:13:41 2014 +0530
@@ -163,6 +163,10 @@
                          quoting = csv.QUOTE_ALL)
         self._write_test(['a\nb',1], '"a\nb","1"',
                          quoting = csv.QUOTE_ALL)
+        self._write_test(['a',None,1], '"a",,1',
+                         quoting = csv.QUOTE_STRINGS)
+        self._write_test(['a',None,1], '"a",,"1"',
+                         quoting = csv.QUOTE_NOTNULL)
 
     def test_write_escape(self):
         self._write_test(['a',1,'p,q'], 'a,1,"p,q"',