bpo-45046: Support context managers in unittest (GH-28045)

Add methods enterContext() and enterClassContext() in TestCase.
Add method enterAsyncContext() in IsolatedAsyncioTestCase.
Add function enterModuleContext().

1 files changed, 5 insertions, 14 deletions

diff --git a/Lib/test/test_importlib/source/test_finder.py b/Lib/test/test_importlib/source/test_finder.py
index 6a23e9d50f6..bed9d56dca8 100644
--- a/Lib/test/test_importlib/source/test_finder.py
+++ b/Lib/test/test_importlib/source/test_finder.py
@@ -157,21 +157,12 @@ class FinderTests(abc.FinderTests):
     def test_no_read_directory(self):
         # Issue #16730
         tempdir = tempfile.TemporaryDirectory()
+        self.enterContext(tempdir)
+        # Since we muck with the permissions, we want to set them back to
+        # their original values to make sure the directory can be properly
+        # cleaned up.
         original_mode = os.stat(tempdir.name).st_mode
-        def cleanup(tempdir):
-            """Cleanup function for the temporary directory.
-
-            Since we muck with the permissions, we want to set them back to
-            their original values to make sure the directory can be properly
-            cleaned up.
-
-            """
-            os.chmod(tempdir.name, original_mode)
-            # If this is not explicitly called then the __del__ method is used,
-            # but since already mucking around might as well explicitly clean
-            # up.
-            tempdir.__exit__(None, None, None)
-        self.addCleanup(cleanup, tempdir)
+        self.addCleanup(os.chmod, tempdir.name, original_mode)
         os.chmod(tempdir.name, stat.S_IWUSR | stat.S_IXUSR)
         finder = self.get_finder(tempdir.name)
         found = self._find(finder, 'doesnotexist')