diff -r ee48728e3695 Tools/parser/test_unparse.py
--- a/Tools/parser/test_unparse.py	Fri Jan 25 15:35:12 2013 +0100
+++ b/Tools/parser/test_unparse.py	Mon Jan 28 09:58:17 2013 +0200
@@ -2,7 +2,6 @@
 import test.support
 import io
 import os
-import random
 import tokenize
 import unparse
 import ast
@@ -242,25 +241,30 @@
 
 
 class DirectoryTestCase(ASTTestCase):
-    """Test roundtrip behaviour on all files in Lib and Lib/test."""
+    """Test roundtrip behaviour on all files in Lib and Lib/test.
+    In case the "cpu" resource is not enabled, behaviour on
+    only one file - test_gramar.py - is tested."""
 
     # test directories, relative to the root of the distribution
     test_directories = 'Lib', os.path.join('Lib', 'test')
 
     def test_files(self):
-        # get names of files to test
-        dist_dir = os.path.join(os.path.dirname(__file__), os.pardir, os.pardir)
 
         names = []
-        for d in self.test_directories:
-            test_dir = os.path.join(dist_dir, d)
-            for n in os.listdir(test_dir):
-                if n.endswith('.py') and not n.startswith('bad'):
-                    names.append(os.path.join(test_dir, n))
+        # Test one file unless the 'cpu' resource is specified.
+        if test.support.is_resource_enabled("cpu"):
+            # get names of files to test
+            dist_dir = os.path.join(
+                os.path.dirname(__file__), os.pardir, os.pardir)
 
-        # Test limited subset of files unless the 'cpu' resource is specified.
-        if not test.support.is_resource_enabled("cpu"):
-            names = random.sample(names, 10)
+            for d in self.test_directories:
+                test_dir = os.path.join(dist_dir, d)
+                for n in os.listdir(test_dir):
+                    if n.endswith('.py') and not n.startswith('bad'):
+                        names.append(os.path.join(test_dir, n))
+        else:
+            names.append(
+                os.path.join(self.test_directories[1], "test_grammar.py"))
 
         for filename in names:
             if test.support.verbose: