pythongh-90522: add test

Subprocess opening /dev/stdin fails if it is a socketpair.

Lib/test/test_asyncio/test_subprocess.py

@@ -401,6 +401,26 @@ async def empty_error():
  self.assertEqual(output, None)
  self.assertEqual(exitcode, 0)
 
+ @unittest.skipIf(sys.platform != 'linux', "Don't have /dev/stdin")
+ def test_devstdin_input(self):
+
+ async def devstdin_input(message):
+ code = 'file = open("/dev/stdin"); data = file.read(); print(len(data))'
+ proc = await asyncio.create_subprocess_exec(
+ sys.executable, '-c', code,
+ stdin=asyncio.subprocess.PIPE,
+ stdout=asyncio.subprocess.PIPE,
+ stderr=asyncio.subprocess.PIPE,
+ close_fds=False,
+ )
+ stdout, stderr = await proc.communicate(message)
+ exitcode = await proc.wait()
+ return (stdout, exitcode)
+
+ output, exitcode = self.loop.run_until_complete(devstdin_input(b'abc'))
+ self.assertEqual(output.rstrip(), b'3')
+ self.assertEqual(exitcode, 0)
+
  def test_cancel_process_wait(self):
  # Issue #23140: cancel Process.wait()