diff -r 5ea81e4c58a7 Lib/lib2to3/tests/test_parser.py
--- a/Lib/lib2to3/tests/test_parser.py	Mon Oct 17 20:44:22 2011 +0200
+++ b/Lib/lib2to3/tests/test_parser.py	Tue Oct 18 13:54:24 2011 +0300
@@ -15,6 +15,8 @@
 # Python imports
 import os
 import unittest
+import warnings
+import subprocess
 
 # Local imports
 from lib2to3.pgen2 import tokenize
@@ -171,7 +173,7 @@
             try:
                 tree = driver.parse_string(source)
             except ParseError as err:
-                print('ParseError on file', filepath, err)
+                warnings.warn('ParseError on file %s (%s)' % (filepath, err))
                 continue
             new = str(tree)
             if diff(filepath, new):
@@ -183,6 +185,7 @@
         driver.parse_string("(z, *y, w) = m\n")
         driver.parse_string("for *z, m in d: pass\n")
 
+
 class TestLiterals(GrammarTest):
 
     def validate(self, s):
@@ -221,7 +224,7 @@
         with open('@', 'w') as f:
             f.write(str(result))
         fn = fn.replace('"', '\\"')
-        return os.system('diff -u "%s" @' % fn)
+        return subprocess.getoutput('diff -u "%s" @' % fn)
     finally:
         try:
             os.remove("@")