Issue #14252: Fix subprocess.Popen.terminate() to not raise an error under Windows when the child process has already exited.

Lib/test/test_subprocess.py

@@ -1078,6 +1078,27 @@ class POSIXProcessTestCase(BaseTestCase):
         getattr(p, method)(*args)
         return p
 
+    def _kill_dead_process(self, method, *args):
+        # Do not inherit file handles from the parent.
+        # It should fix failures on some platforms.
+        p = subprocess.Popen([sys.executable, "-c", """if 1:
+                             import sys, time
+                             sys.stdout.write('x\\n')
+                             sys.stdout.flush()
+                             """],
+                             close_fds=True,
+                             stdin=subprocess.PIPE,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        # Wait for the interpreter to be completely initialized before
+        # sending any signal.
+        p.stdout.read(1)
+        # The process should end after this
+        time.sleep(1)
+        # This shouldn't raise even though the child is now dead
+        getattr(p, method)(*args)
+        p.communicate()
+
     def test_send_signal(self):
         p = self._kill_process('send_signal', signal.SIGINT)
         _, stderr = p.communicate()
@@ -1096,6 +1117,18 @@ class POSIXProcessTestCase(BaseTestCase):
         self.assertStderrEqual(stderr, b'')
         self.assertEqual(p.wait(), -signal.SIGTERM)
 
+    def test_send_signal_dead(self):
+        # Sending a signal to a dead process
+        self._kill_dead_process('send_signal', signal.SIGINT)
+
+    def test_kill_dead(self):
+        # Killing a dead process
+        self._kill_dead_process('kill')
+
+    def test_terminate_dead(self):
+        # Terminating a dead process
+        self._kill_dead_process('terminate')
+
     def check_close_std_fds(self, fds):
         # Issue #9905: test that subprocess pipes still work properly with
         # some standard fds closed
@@ -1662,6 +1695,31 @@ class Win32ProcessTestCase(BaseTestCase):
         returncode = p.wait()
         self.assertNotEqual(returncode, 0)
 
+    def _kill_dead_process(self, method, *args):
+        p = subprocess.Popen([sys.executable, "-c", """if 1:
+                             import sys, time
+                             sys.stdout.write('x\\n')
+                             sys.stdout.flush()
+                             sys.exit(42)
+                             """],
+                             stdin=subprocess.PIPE,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        self.addCleanup(p.stdout.close)
+        self.addCleanup(p.stderr.close)
+        self.addCleanup(p.stdin.close)
+        # Wait for the interpreter to be completely initialized before
+        # sending any signal.
+        p.stdout.read(1)
+        # The process should end after this
+        time.sleep(1)
+        # This shouldn't raise even though the child is now dead
+        getattr(p, method)(*args)
+        _, stderr = p.communicate()
+        self.assertStderrEqual(stderr, b'')
+        rc = p.wait()
+        self.assertEqual(rc, 42)
+
     def test_send_signal(self):
         self._kill_process('send_signal', signal.SIGTERM)
 
@@ -1671,6 +1729,15 @@ class Win32ProcessTestCase(BaseTestCase):
     def test_terminate(self):
         self._kill_process('terminate')
 
+    def test_send_signal_dead(self):
+        self._kill_dead_process('send_signal', signal.SIGTERM)
+
+    def test_kill_dead(self):
+        self._kill_dead_process('kill')
+
+    def test_terminate_dead(self):
+        self._kill_dead_process('terminate')
+
 
 # The module says:
 #   "NB This only works (and is only relevant) for UNIX."