gh-160596: Fix error message in asyncio.proactor_events.sendto() (#160597)

Author: aisk

Lib/asyncio/proactor_events.py

@@ -489,8 +489,8 @@ def _force_close(self, exc):
 
     def sendto(self, data, addr=None):
         if not isinstance(data, (bytes, bytearray, memoryview)):
-            raise TypeError('data argument must be bytes-like object (%r)',
-                            type(data))
+            raise TypeError(f'data argument must be a bytes-like object, '
+                            f'not {type(data).__name__!r}')
 
         if self._address is not None and addr not in (None, self._address):
             raise ValueError(

Lib/test/test_asyncio/test_proactor_events.py

@@ -691,7 +691,9 @@ def test_sendto_error_received_connected(self):
 
     def test_sendto_str(self):
         transport = self.datagram_transport()
-        self.assertRaises(TypeError, transport.sendto, 'str', ())
+        self.assertRaisesRegex(
+            TypeError, "^data argument must be a bytes-like object, not 'str'$",
+            transport.sendto, 'str', ())
 
     def test_sendto_connected_addr(self):
         transport = self.datagram_transport(address=('0.0.0.0', 1))

Misc/NEWS.d/next/Library/2026-10-24-22-32-23.gh-issue-160596.RKll-Z.rst

@@ -0,0 +1,2 @@
+Fix the error message for invalid data passed to
+:meth:`!asyncio.proactor_events.sendto`.