Index: Lib/unittest/test/test_runner.py
===================================================================
--- Lib/unittest/test/test_runner.py	(revision 86934)
+++ Lib/unittest/test/test_runner.py	(working copy)
@@ -265,6 +265,8 @@
 
         # no args -> all the warnings are printed, unittest warnings only once
         p = subprocess.Popen([sys.executable, '_test_warnings.py'], **opts)
+        self.addCleanup(p.stdout.close)
+        self.addCleanup(p.stderr.close)
         out, err = get_parse_out_err(p)
         self.assertIn(b'OK', err)
         # check that the total number of warnings in the output is correct
@@ -286,6 +288,8 @@
         # in all these cases no warnings are printed
         for args in args_list:
             p = subprocess.Popen(args, **opts)
+            self.addCleanup(p.stdout.close)
+            self.addCleanup(p.stderr.close)
             out, err = get_parse_out_err(p)
             self.assertIn(b'OK', err)
             self.assertEqual(len(out), 0)
@@ -295,6 +299,8 @@
         #                                     unittest warnings only once
         p = subprocess.Popen([sys.executable, '_test_warnings.py', 'always'],
                              **opts)
+        self.addCleanup(p.stdout.close)
+        self.addCleanup(p.stderr.close)
         out, err = get_parse_out_err(p)
         self.assertIn(b'OK', err)
         self.assertEqual(len(out), 14)