add depreciation and update tests

Author: Aniketsy

Lib/tempfile.py

@@ -556,7 +556,17 @@ def __iter__(self):
         for line in self.file:
             yield line
 
-_TemporaryFileWrapper = TemporaryFileWrapper
+# _TemporaryFileWrapper is deprecated in favor of the public
+def __getattr__(name):
+    if name == "_TemporaryFileWrapper":
+        _warnings._deprecated(
+            "tempfile._TemporaryFileWrapper",
+            message="{name} is deprecated and will be removed in a future "
+                    "version. Use tempfile.TemporaryFileWrapper instead.",
+            remove=(3, 16),
+        )
+        return TemporaryFileWrapper
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")
 
 def NamedTemporaryFile(mode='w+b', buffering=-1, encoding=None,
                        newline=None, suffix=None, prefix=None,

Lib/test/test_tempfile.py

@@ -981,12 +981,23 @@ def do_create(self, dir=None, pre="", suf="", delete=True):
 
     def test_basic(self):
         # NamedTemporaryFile can create files
-        self.do_create()
+        f = self.do_create()
+        self.assertIsInstance(f, tempfile.TemporaryFileWrapper)
         self.do_create(pre="a")
         self.do_create(suf="b")
         self.do_create(pre="a", suf="b")
         self.do_create(pre="aa", suf=".txt")
 
+    def test_in_all(self):
+        self.assertIn("TemporaryFileWrapper", tempfile.__all__)
+
+    def test_deprecated_TemporaryFileWrapper_alias(self):
+        # gh-152586: _TemporaryFileWrapper is a deprecated alias
+        # for the public TemporaryFileWrapper class.
+        with self.assertWarns(DeprecationWarning):
+            obj = tempfile._TemporaryFileWrapper
+        self.assertIs(obj, tempfile.TemporaryFileWrapper)
+
     def test_method_lookup(self):
         # Issue #18879: Looking up a temporary file method should keep it
         # alive long enough.
@@ -1186,7 +1197,7 @@ def test_bad_encoding(self):
     def test_unexpected_error(self):
         dir = tempfile.mkdtemp()
         self.addCleanup(os_helper.rmtree, dir)
-        with mock.patch('tempfile._TemporaryFileWrapper') as mock_ntf, \
+        with mock.patch('tempfile.TemporaryFileWrapper') as mock_ntf, \
              mock.patch('io.open', mock.mock_open()) as mock_open:
             mock_ntf.side_effect = KeyboardInterrupt()
             with self.assertRaises(KeyboardInterrupt):
@@ -1196,18 +1207,6 @@ def test_unexpected_error(self):
 
     # How to test the mode and bufsize parameters?
 
-class TestTemporaryFileWrapper(BaseTestCase):
-    """Test TemporaryFileWrapper."""
-
-    def test_public_name(self):
-        self.assertIs(tempfile.TemporaryFileWrapper, tempfile._TemporaryFileWrapper)
-
-    def test_in_all(self):
-        self.assertIn("TemporaryFileWrapper", tempfile.__all__)
-
-    def test_is_return_type_of_named_temporary_file(self):
-        with tempfile.NamedTemporaryFile() as f:
-            self.assertIsInstance(f, tempfile.TemporaryFileWrapper)
 
 class TestSpooledTemporaryFile(BaseTestCase):
     """Test SpooledTemporaryFile()."""