gh-119690: Adds Unicode support for named pipes in _winapi (GH-119717)

(cherry picked from commit 78d697b7d5)

Co-authored-by: Steve Dower <steve.dower@python.org>

Lib/test/test_winapi.py

@@ -7,7 +7,7 @@ import re
 import threading
 import time
 import unittest
-from test.support import import_helper
+from test.support import import_helper, os_helper
 
 _winapi = import_helper.import_module('_winapi', required_on=['win'])
 
@@ -127,3 +127,35 @@ class WinAPITests(unittest.TestCase):
 
         # Should contain "PROGRA~" but we can't predict the number
         self.assertIsNotNone(re.match(r".\:\\PROGRA~\d", actual.upper()), actual)
+
+    def test_namedpipe(self):
+        pipe_name = rf"\\.\pipe\LOCAL\{os_helper.TESTFN}"
+
+        # Pipe does not exist, so this raises
+        with self.assertRaises(FileNotFoundError):
+            _winapi.WaitNamedPipe(pipe_name, 0)
+
+        pipe = _winapi.CreateNamedPipe(
+            pipe_name,
+            _winapi.PIPE_ACCESS_DUPLEX,
+            8, # 8=PIPE_REJECT_REMOTE_CLIENTS
+            2, # two instances available
+            32, 32, 0, 0)
+        self.addCleanup(_winapi.CloseHandle, pipe)
+
+        # Pipe instance is available, so this passes
+        _winapi.WaitNamedPipe(pipe_name, 0)
+
+        with open(pipe_name, 'w+b') as pipe2:
+            # No instances available, so this times out
+            # (WinError 121 does not get mapped to TimeoutError)
+            with self.assertRaises(OSError):
+                _winapi.WaitNamedPipe(pipe_name, 0)
+
+            _winapi.WriteFile(pipe, b'testdata')
+            self.assertEqual(b'testdata', pipe2.read(8))
+
+            self.assertEqual((b'', 0), _winapi.PeekNamedPipe(pipe, 8)[:2])
+            pipe2.write(b'testdata')
+            pipe2.flush()
+            self.assertEqual((b'testdata', 8), _winapi.PeekNamedPipe(pipe, 8)[:2])