Fix test_version on Python 3.4

Since Python 3.4, argparse has been printing the version on stdout rather than
on stderr as it used to. We should fix this now because:
- this is an issue when packaging oslo-config in Debian Sid, which uses Python
  3.4;
- it will be needed when Openstack switches to 3.4 anyway.

Change-Id: I6a84009acb8621d62465c4cd2573200a07b6b4ab

1 files changed, 9 insertions, 2 deletions

diff --git a/tests/test_cfg.py b/tests/test_cfg.py
index f1f576b..a4aaf42 100644
--- a/tests/test_cfg.py
+++ b/tests/test_cfg.py
@@ -479,9 +479,16 @@ class CliSpecialOptsTestCase(BaseTestCase):
         self.assertTrue('--config-file' in sys.stdout.getvalue())
 
     def test_version(self):
-        self.useFixture(fixtures.MonkeyPatch('sys.stderr', moves.StringIO()))
+        # In Python 3.4+, argparse prints the version on stdout; before 3.4, it
+        # printed it on stderr.
+        if sys.version_info >= (3, 4):
+            stream_name = 'stdout'
+        else:
+            stream_name = 'stderr'
+        self.useFixture(fixtures.MonkeyPatch("sys.%s" % stream_name,
+                                             moves.StringIO()))
         self.assertRaises(SystemExit, self.conf, ['--version'])
-        self.assertTrue('1.0' in sys.stderr.getvalue())
+        self.assertTrue('1.0' in getattr(sys, stream_name).getvalue())
 
     def test_config_file(self):
         paths = self.create_tempfiles([('1', '[DEFAULT]'),