Using lists is faster than cStringIO.

tests/subprocess2_test.py

 #!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Unit tests for subprocess2.py."""
 
 import logging
 import optparse
 import os
@@ skipping 382 matching lines @@
   def test_stdin_unicode(self):
     def fn(c, e, un):
       stdin = u'0123456789'
       res = subprocess2.communicate(
           e + ['--read'],
           stdin=stdin,
           universal_newlines=un)
       self._check_res(res, None, None, 10)
     self._run_test(fn)
 
+  def test_stdin_empty(self):
+    def fn(c, e, un):
+      stdin = ''
+      res = subprocess2.communicate(
+          e + ['--read'],
+          stdin=stdin,
+          universal_newlines=un)
+      self._check_res(res, None, None, 0)
+    self._run_test(fn)
+
   def test_stdin_void(self):
     res = subprocess2.communicate(self.exe + ['--read'], stdin=VOID)
     self._check_res(res, None, None, 0)
 
   def test_stdin_void_stdout_timeout(self):
     # Make sure a mix of VOID, PIPE and timeout works.
     def fn(c, e, un):
       res = subprocess2.communicate(
           e + ['--stdout', '--read'],
           stdin=VOID,
@@ skipping 219 matching lines @@
   return options.return_value
 
 
 if __name__ == '__main__':
   logging.basicConfig(level=
       [logging.WARNING, logging.INFO, logging.DEBUG][
         min(2, sys.argv.count('-v'))])
   if len(sys.argv) > 1 and sys.argv[1] == '--child':
     sys.exit(child_main(sys.argv[2:]))
   unittest.main()