gh-93243: Make smtpd private before porting its users (GH-93246)

gh-93243

This PR is required to reduce diffs of the following porting (no need to either maintain documentation and tests consistent with each porting step, or try to port everything and remove smtpd in a single PR).

Automerge-Triggered-By: GH:warsaw

Author: arhadthedev

Doc/library/email.rst

@@ -147,6 +147,3 @@ Legacy API:
    Module :mod:`mailbox`
       Tools for creating, reading, and managing collections of messages on disk
       using a variety standard formats.
-
-   Module :mod:`smtpd`
-      SMTP server framework (primarily useful for testing)

Doc/library/smtpd.rst

@@ -27,7 +27,6 @@ backwards compatibility. They have been superseded by other modules.
    optparse.rst
    ossaudiodev.rst
    pipes.rst
-   smtpd.rst
    sndhdr.rst
    spwd.rst
    sunau.rst

Doc/library/superseded.rst

@@ -299,6 +299,14 @@ Removed
   (and corresponding ``EXPERIMENTAL_ISOLATED_SUBINTERPRETERS``)
   have been removed.
 
+* ``smtpd`` has been removed according to the schedule in :pep:`594`,
+  having been deprecated in Python 3.4.7 and 3.5.4.
+  Use aiosmtpd_ PyPI module or any other
+  :mod:`asyncio`-based server instead.
+  (Contributed by Oleg Iarygin in :gh:`93243`.)
+
+.. _aiosmtpd: https://pypi.org/project/aiosmtpd/
+
 * Remove ``io.OpenWrapper`` and ``_pyio.OpenWrapper``, deprecated in Python
   3.10: just use :func:`open` instead. The :func:`open` (:func:`io.open`)
   function is a built-in function. Since Python 3.10, :func:`_pyio.open` is
@@ -382,6 +390,10 @@ Changes in the Python API
   to :term:`filesystem encoding and error handler`.
   Argument files should be encoded in UTF-8 instead of ANSI Codepage on Windows.
 
+* Removed the ``asyncore``-based ``smtpd`` module deprecated in Python 3.4.7
+  and 3.5.4.  A recommended replacement is the
+  :mod:`asyncio`-based aiosmtpd_ PyPI module.
+
 * :func:`shlex.split`: Passing ``None`` for *s* argument now raises an
   exception, rather than reading :data:`sys.stdin`. The feature was deprecated
   in Python 3.9.

Doc/whatsnew/3.12.rst

@@ -1,4 +1,4 @@
-"""Mock socket module used by the smtpd and smtplib tests.
+"""Mock socket module used by the smtplib tests.
 """
 
 # imported for _GLOBAL_DEFAULT_TIMEOUT
@@ -33,7 +33,7 @@ def close(self):
 
 
 class MockSocket:
-    """Mock socket object used by smtpd and smtplib tests.
+    """Mock socket object used by the smtplib tests.
     """
     def __init__(self, family=None):
         global _reply_data

Lib/test/mock_socket.py

@@ -77,25 +77,16 @@
 import time
 import socket
 import collections
-from warnings import _deprecated, warn
+from test.support.import_helper import import_module
+from warnings import warn
 from email._header_value_parser import get_addr_spec, get_angle_addr
 
 __all__ = [
     "SMTPChannel", "SMTPServer", "DebuggingServer", "PureProxy",
 ]
 
-_DEPRECATION_MSG = ('The {name} module is deprecated and unmaintained and will '
-                    'be removed in Python {remove}.  Please see aiosmtpd '
-                    '(https://aiosmtpd.readthedocs.io/) for the recommended '
-                    'replacement.')
-_deprecated(__name__, _DEPRECATION_MSG, remove=(3, 12))
-
-
-# These are imported after the above warning so that users get the correct
-# deprecation warning.
-import asyncore
-import asynchat
-
+asyncore = import_module('asyncore', deprecated=True)
+asynchat = import_module('asynchat', deprecated=True)
 
 program = sys.argv[0]
 __version__ = 'Python SMTP proxy version 0.3'

Lib/smtpd.py renamed to Lib/test/smtpd.py

@@ -61,9 +61,10 @@
 from socketserver import (ThreadingUDPServer, DatagramRequestHandler,
                           ThreadingTCPServer, StreamRequestHandler)
 
+with warnings.catch_warnings():
+    from . import smtpd
 
 asyncore = warnings_helper.import_deprecated('asyncore')
-smtpd = warnings_helper.import_deprecated('smtpd')
 
 
 try: