Merged revisions 71881 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/branches/py3k

................
  r71881 | walter.doerwald | 2009-04-25 14:48:43 +0200 (Sa, 25 Apr 2009) | 14 lines

  Merged revisions 71875 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r71875 | walter.doerwald | 2009-04-25 14:15:07 +0200 (Sa, 25 Apr 2009) | 7 lines

    Issue #5837: Certain sequences of calls to set() and unset() for
    support.EnvironmentVarGuard objects restored the environment variables
    incorrectly on __exit__.

    Fix this by recording the initial value of each environment variable on the
    first access in set() or unset().
  ........
................

diff --git a/Lib/test/support.py b/Lib/test/support.py
index 68791d514f96b1895d3675a288ecb3284bbff442..2e7195beac6e7efa0165af2ebb8ee2f714e675d2 100644 (file)
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -441,30 +441,31 @@ class EnvironmentVarGuard(object):
     a context manager."""
 
     def __init__(self):
-        self._environ = os.environ
-        self._unset = set()
-        self._reset = dict()
+        self._changed = {}
 
     def set(self, envvar, value):
-        if envvar not in self._environ:
-            self._unset.add(envvar)
-        else:
-            self._reset[envvar] = self._environ[envvar]
-        self._environ[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
 
     def unset(self, envvar):
-        if envvar in self._environ:
-            self._reset[envvar] = self._environ[envvar]
-            del self._environ[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]
 
     def __enter__(self):
         return self
 
     def __exit__(self, *ignore_exc):
-        for envvar, value in self._reset.items():
-            self._environ[envvar] = value
-        for unset in self._unset:
-            del self._environ[unset]
+        for (k, v) in self._changed.items():
+            if v is None:
+                if k in os.environ:
+                    del os.environ[k]
+            else:
+                os.environ[k] = v
 
 class TransientResource(object):
 

diff --git a/Misc/NEWS b/Misc/NEWS
index 8c6e6302d7dfc578fbc4147a42ef504c6b752371..5e9b9df8a08013d29f7dfb0aa09c632da17947c2 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -119,6 +119,13 @@ Build
 - Issue #5359: Readd the Berkley-DB detection code to allow _dbm be built
   using Berkley-DB.
 
+Tests
+-----
+
+- Issue #5837: Certain sequences of calls to set() and unset() for
+  support.EnvironmentVarGuard objects restored the environment variables
+  incorrectly on __exit__.
+
 
 What's New in Python 3.0.1?
 ===========================