Issue #23197, asyncio: On SSL handshake failure, check if the waiter is

cancelled before setting its exception.

* Add unit tests for this case.
* Cleanup also sslproto.py

Lib/test/test_asyncio/test_sslproto.py

@@ -0,0 +1,45 @@
+"""Tests for asyncio/sslproto.py."""
+
+import unittest
+from unittest import mock
+
+import asyncio
+from asyncio import sslproto
+from asyncio import test_utils
+
+
+class SslProtoHandshakeTests(test_utils.TestCase):
+
+    def setUp(self):
+        self.loop = asyncio.new_event_loop()
+        self.set_event_loop(self.loop)
+
+    def test_cancel_handshake(self):
+        # Python issue #23197: cancelling an handshake must not raise an
+        # exception or log an error, even if the handshake failed
+        sslcontext = test_utils.dummy_ssl_context()
+        app_proto = asyncio.Protocol()
+        waiter = asyncio.Future(loop=self.loop)
+        ssl_proto = sslproto.SSLProtocol(self.loop, app_proto, sslcontext,
+                                         waiter)
+        handshake_fut = asyncio.Future(loop=self.loop)
+
+        def do_handshake(callback):
+            exc = Exception()
+            callback(exc)
+            handshake_fut.set_result(None)
+            return []
+
+        waiter.cancel()
+        transport = mock.Mock()
+        sslpipe = mock.Mock()
+        sslpipe.do_handshake.side_effect = do_handshake
+        with mock.patch('asyncio.sslproto._SSLPipe', return_value=sslpipe):
+            ssl_proto.connection_made(transport)
+
+        with test_utils.disable_logger():
+            self.loop.run_until_complete(handshake_fut)
+
+
+if __name__ == '__main__':
+    unittest.main()