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.

1 files changed, 7 insertions, 1 deletions

diff --git a/Doc/library/test.rst b/Doc/library/test.rst
index ba2c3b8..b4a6c7a 100644
--- a/Doc/library/test.rst
+++ b/Doc/library/test.rst
@@ -401,9 +401,14 @@ The :mod:`test.test_support` module defines the following classes:
 .. class:: EnvironmentVarGuard()
 
    Class used to temporarily set or unset environment variables.  Instances can be
-   used as a context manager.
+   used as a context manager and have a complete dictionary interface for
+   querying/modifying the underlying ``os.environ``. After exit from the context
+   manager all changes to environment variables done through this instance will
+   be rolled back.
 
    .. versionadded:: 2.6
+   .. versionchanged:: 2.7
+      Added dictionary interface.
 
 
 .. method:: EnvironmentVarGuard.set(envvar, value)
@@ -415,6 +420,7 @@ The :mod:`test.test_support` module defines the following classes:
 
    Temporarily unset the environment variable ``envvar``.
 
+
 .. class:: WarningsRecorder()
 
    Class used to record warnings for unit tests. See documentation of