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

Add methods enterContext() and enterClassContext() in TestCase.
Add method enterAsyncContext() in IsolatedAsyncioTestCase.
Add function enterModuleContext().
(cherry picked from commit 086c6b1b0fe8d47ebd15512d7bdcb64c60a360f0)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

1 files changed, 3 insertions, 9 deletions

diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
index f44b8d0..28e5e90 100644
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -53,19 +53,13 @@ class PosixTester(unittest.TestCase):
 
     def setUp(self):
         # create empty file
+        self.addCleanup(os_helper.unlink, os_helper.TESTFN)
         with open(os_helper.TESTFN, "wb"):
             pass
-        self.teardown_files = [ os_helper.TESTFN ]
-        self._warnings_manager = warnings_helper.check_warnings()
-        self._warnings_manager.__enter__()
+        self.enterContext(warnings_helper.check_warnings())
         warnings.filterwarnings('ignore', '.* potential security risk .*',
                                 RuntimeWarning)
 
-    def tearDown(self):
-        for teardown_file in self.teardown_files:
-            os_helper.unlink(teardown_file)
-        self._warnings_manager.__exit__(None, None, None)
-
     def testNoArgFunctions(self):
         # test posix functions which take no arguments and have
         # no side-effects which we need to cleanup (e.g., fork, wait, abort)
@@ -973,8 +967,8 @@ class PosixTester(unittest.TestCase):
 
         self.assertTrue(hasattr(testfn_st, 'st_flags'))
 
+        self.addCleanup(os_helper.unlink, _DUMMY_SYMLINK)
         os.symlink(os_helper.TESTFN, _DUMMY_SYMLINK)
-        self.teardown_files.append(_DUMMY_SYMLINK)
         dummy_symlink_st = os.lstat(_DUMMY_SYMLINK)
 
         def chflags_nofollow(path, flags):