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, 5 insertions, 9 deletions

diff --git a/Lib/test/test_ntpath.py b/Lib/test/test_ntpath.py
index a077c78..ade0790 100644
--- a/Lib/test/test_ntpath.py
+++ b/Lib/test/test_ntpath.py
@@ -124,12 +124,11 @@ class TestNtpath(unittest.TestCase):
         tester("ntpath.normpath('//machine/share//a/b')", r'\\machine\share\a\b')
 
     def test_expandvars(self):
-        oldenv = os.environ.copy()
-        try:
-            os.environ.clear()
-            os.environ["foo"] = "bar"
-            os.environ["{foo"] = "baz1"
-            os.environ["{foo}"] = "baz2"
+        with test_support.EnvironmentVarGuard() as env:
+            env.clear()
+            env["foo"] = "bar"
+            env["{foo"] = "baz1"
+            env["{foo}"] = "baz2"
             tester('ntpath.expandvars("foo")', "foo")
             tester('ntpath.expandvars("$foo bar")', "bar bar")
             tester('ntpath.expandvars("${foo}bar")', "barbar")
@@ -149,9 +148,6 @@ class TestNtpath(unittest.TestCase):
             tester('ntpath.expandvars("%?bar%")', "%?bar%")
             tester('ntpath.expandvars("%foo%%bar")', "bar%bar")
             tester('ntpath.expandvars("\'%foo%\'%bar")', "\'%foo%\'%bar")
-        finally:
-            os.environ.clear()
-            os.environ.update(oldenv)
 
     def test_abspath(self):
         # ntpath.abspath() can only be used on a system with the "nt" module