From 155374d95d8ecd235d3a3edd92dd6f6a23d59f11 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Walter=20D=C3=B6rwald?= <walter@livinglogic.de>
Date: Fri, 1 May 2009 19:58:58 +0000
Subject: Merged revisions 72167 via svnmerge from
 svn+ssh://pythondev@svn.python.org/python/trunk

........
  r72167 | walter.doerwald | 2009-05-01 19:35:37 +0200 (Fr, 01 Mai 2009) | 5 lines

  Make test.test_support.EnvironmentVarGuard behave like a dictionary.

  All changes are mirrored to the underlying os.environ dict, but rolled back
  on exit from the with block.
........
---
 Lib/test/support.py | 43 ++++++++++++++++++++++++++++++++-----------
 1 file changed, 32 insertions(+), 11 deletions(-)

(limited to 'Lib/test/support.py')

diff --git a/Lib/test/support.py b/Lib/test/support.py
index bdc61645ad..df114a2188 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -13,6 +13,7 @@ import shutil
 import warnings
 import unittest
 import importlib
+import collections
 
 __all__ = ["Error", "TestFailed", "ResourceDenied", "import_module",
            "verbose", "use_resources", "max_memuse", "record_original_stdout",
@@ -510,26 +511,45 @@ class CleanImport(object):
         sys.modules.update(self.original_modules)
 
 
-class EnvironmentVarGuard(object):
+class EnvironmentVarGuard(collections.MutableMapping):
 
     """Class to help protect the environment variable properly.  Can be used as
     a context manager."""
 
     def __init__(self):
+        self._environ = os.environ
         self._changed = {}
 
-    def set(self, envvar, value):
+    def __getitem__(self, envvar):
+        return self._environ[envvar]
+
+    def __setitem__(self, envvar, value):
         # Remember the initial value on the first access
         if envvar not in self._changed:
-            self._changed[envvar] = os.environ.get(envvar)
-        os.environ[envvar] = value
+            self._changed[envvar] = self._environ.get(envvar)
+        self._environ[envvar] = value
 
-    def unset(self, envvar):
+    def __delitem__(self, envvar):
         # Remember the initial value on the first access
         if envvar not in self._changed:
-            self._changed[envvar] = os.environ.get(envvar)
-        if envvar in os.environ:
-            del os.environ[envvar]
+            self._changed[envvar] = self._environ.get(envvar)
+        if envvar in self._environ:
+            del self._environ[envvar]
+
+    def keys(self):
+        return self._environ.keys()
+
+    def __iter__(self):
+        return iter(self._environ)
+
+    def __len__(self):
+        return len(self._environ)
+
+    def set(self, envvar, value):
+        self[envvar] = value
+
+    def unset(self, envvar):
+        del self[envvar]
 
     def __enter__(self):
         return self
@@ -537,10 +557,11 @@ class EnvironmentVarGuard(object):
     def __exit__(self, *ignore_exc):
         for (k, v) in self._changed.items():
             if v is None:
-                if k in os.environ:
-                    del os.environ[k]
+                if k in self._environ:
+                    del self._environ[k]
             else:
-                os.environ[k] = v
+                self._environ[k] = v
+
 
 class TransientResource(object):
 
-- 
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