From c80504fb6954c8aabc97e79116fd93bb8d55a03c Mon Sep 17 00:00:00 2001
From: "Gregory P. Smith" <greg@krypto.org>
Date: Sat, 28 May 2011 09:06:02 -0700
Subject: [PATCH] Fix ProcessTestCasePOSIXPurePython to test the module from
 import when _posixsubprocess doesn't exist rather than simply stubbing it out
 after the fact.  This adds coverage for the RuntimeWarning as well as using
 the pure python _create_pipe instead of using _posixsubprocess.cloexec_pipe
 unintentionally with the pure python code.

Ironically: I don't think any platform should ever actually _use_ the
pure Python subprocess code on POSIX platforms anymore.  This at least
tests it properly in this stable branch.  The pure python code for
this is likely to be removed in 3.3.
---
 Lib/test/test_subprocess.py | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 776e1437c4ab..08d2653102ca 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1498,15 +1498,23 @@ def tearDown(self):
 @unittest.skipUnless(getattr(subprocess, '_posixsubprocess', False),
                      "_posixsubprocess extension module not found.")
 class ProcessTestCasePOSIXPurePython(ProcessTestCase, POSIXProcessTestCase):
-    def setUp(self):
-        subprocess._posixsubprocess = None
-        ProcessTestCase.setUp(self)
-        POSIXProcessTestCase.setUp(self)
+    @classmethod
+    def setUpClass(cls):
+        global subprocess
+        assert subprocess._posixsubprocess
+        # Reimport subprocess while forcing _posixsubprocess to not exist.
+        with support.check_warnings(('.*_posixsubprocess .* not being used.*',
+                                     RuntimeWarning)):
+            subprocess = support.import_fresh_module(
+                    'subprocess', blocked=['_posixsubprocess'])
+        assert not subprocess._posixsubprocess
 
-    def tearDown(self):
-        subprocess._posixsubprocess = sys.modules['_posixsubprocess']
-        POSIXProcessTestCase.tearDown(self)
-        ProcessTestCase.tearDown(self)
+    @classmethod
+    def tearDownClass(cls):
+        global subprocess
+        # Reimport subprocess as it should be, restoring order to the universe.
+        subprocess = support.import_fresh_module('subprocess')
+        assert subprocess._posixsubprocess
 
 
 class HelperFunctionTests(unittest.TestCase):