# HG changeset patch
# User Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
# Date 1329166573 -3600
# Branch issue13041
# Node ID 56846891a2b6d7f9cabecfb3746cd6fa64995c21
# Parent  e9cf34d56ff1fd1f5c7c67c50075e3b07a1d31c5
issue13041: autodetect terminal width

The tests are corrected to use COLUMNS override.

diff --git a/Lib/argparse.py b/Lib/argparse.py
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -89,6 +89,7 @@
 import re as _re
 import sys as _sys
 import textwrap as _textwrap
+import shutil as _shutil
 
 from gettext import gettext as _, ngettext
 
@@ -156,10 +157,7 @@
 
         # default setting for width
         if width is None:
-            try:
-                width = int(_os.environ['COLUMNS'])
-            except (KeyError, ValueError):
-                width = 80
+            width = _shutil.get_terminal_size().columns
             width -= 2
 
         self._prog = prog
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -31,9 +31,9 @@
     def setUp(self):
         # The tests assume that line wrapping occurs at 80 columns, but this
         # behaviour can be overridden by setting the COLUMNS environment
-        # variable.  To ensure that this assumption is true, unset COLUMNS.
+        # variable.  To ensure that this width is used, set COLUMNS=80.
         env = support.EnvironmentVarGuard()
-        env.unset("COLUMNS")
+        env['COLUMNS'] = '80'
         self.addCleanup(env.__exit__)