Fixes Issue #26373: subprocess.Popen.communicate now correctly ignores

BrokenPipeError when the child process dies before .communicate()
is called in more (all?) circumstances.

1 files changed, 47 insertions, 0 deletions

diff --git a/Lib/test/test_subprocess.py b/Lib/test/test_subprocess.py
index 9c7aa93..a5ecf67 100644
--- a/Lib/test/test_subprocess.py
+++ b/Lib/test/test_subprocess.py
@@ -1,4 +1,5 @@
 import unittest
+from unittest import mock
 from test.support import script_helper
 from test import support
 import subprocess
@@ -1240,6 +1241,52 @@ class ProcessTestCase(BaseTestCase):
         fds_after_exception = os.listdir(fd_directory)
         self.assertEqual(fds_before_popen, fds_after_exception)
 
+    def test_communicate_BrokenPipeError_stdin_close(self):
+        # By not setting stdout or stderr or a timeout we force the fast path
+        # that just calls _stdin_write() internally due to our mock.
+        proc = subprocess.Popen([sys.executable, '-c', 'pass'])
+        with proc, mock.patch.object(proc, 'stdin') as mock_proc_stdin:
+            mock_proc_stdin.close.side_effect = BrokenPipeError
+            proc.communicate()  # Should swallow BrokenPipeError from close.
+            mock_proc_stdin.close.assert_called_with()
+
+    def test_communicate_BrokenPipeError_stdin_write(self):
+        # By not setting stdout or stderr or a timeout we force the fast path
+        # that just calls _stdin_write() internally due to our mock.
+        proc = subprocess.Popen([sys.executable, '-c', 'pass'])
+        with proc, mock.patch.object(proc, 'stdin') as mock_proc_stdin:
+            mock_proc_stdin.write.side_effect = BrokenPipeError
+            proc.communicate(b'stuff')  # Should swallow the BrokenPipeError.
+            mock_proc_stdin.write.assert_called_once_with(b'stuff')
+            mock_proc_stdin.close.assert_called_once_with()
+
+    def test_communicate_BrokenPipeError_stdin_flush(self):
+        # Setting stdin and stdout forces the ._communicate() code path.
+        # python -h exits faster than python -c pass (but spams stdout).
+        proc = subprocess.Popen([sys.executable, '-h'],
+                                stdin=subprocess.PIPE,
+                                stdout=subprocess.PIPE)
+        with proc, mock.patch.object(proc, 'stdin') as mock_proc_stdin, \
+                open('/dev/null', 'wb') as dev_null:
+            mock_proc_stdin.flush.side_effect = BrokenPipeError
+            # because _communicate registers a selector using proc.stdin...
+            mock_proc_stdin.fileno.return_value = dev_null.fileno()
+            # _communicate() should swallow BrokenPipeError from flush.
+            proc.communicate(b'stuff')
+            mock_proc_stdin.flush.assert_called_once_with()
+
+    def test_communicate_BrokenPipeError_stdin_close_with_timeout(self):
+        # Setting stdin and stdout forces the ._communicate() code path.
+        # python -h exits faster than python -c pass (but spams stdout).
+        proc = subprocess.Popen([sys.executable, '-h'],
+                                stdin=subprocess.PIPE,
+                                stdout=subprocess.PIPE)
+        with proc, mock.patch.object(proc, 'stdin') as mock_proc_stdin:
+            mock_proc_stdin.close.side_effect = BrokenPipeError
+            # _communicate() should swallow BrokenPipeError from close.
+            proc.communicate(timeout=999)
+            mock_proc_stdin.close.assert_called_once_with()
+
 
 class RunFuncTestCase(BaseTestCase):
     def run_python(self, code, **kwargs):