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[3.14] gh-140482: Avoid changing terminal settings in test_pty (gh-142202) #142239

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Merged
colesbury merged 2 commits into from
Dec 5, 2025
Merged

[3.14] gh-140482: Avoid changing terminal settings in test_pty (gh-142202) #142239

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979d5a3
gh-140482: Avoid changing terminal settings in test_pty (gh-142202)
colesbury Dec 3, 2025
a16651a
No take_bytes() in 3.14
colesbury Dec 3, 2025
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gh-140482: Avoid changing terminal settings in test_pty (gh-142202) 
The previous test_spawn_doesnt_hang test had a few problems:

* It would cause ENV CHANGED failures if other tests were running
  concurrently due to stty changes
* Typing while the test was running could cause it to fail
(cherry picked from commit c0c6514)

Co-authored-by: Sam Gross <colesbury@gmail.com>
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@colesbury @miss-islington
colesbury authored and miss-islington committed Dec 3, 2025
commit 979d5a3b4c414c39b459347947209819cb789244
40 changes: 20 additions & 20 deletions Lib/test/test_pty.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,6 @@
is_android, is_apple_mobile, is_wasm32, reap_children, verbose
)
from test.support.import_helper import import_module
from test.support.os_helper import TESTFN, unlink

# Skip these tests if termios is not available
import_module('termios')
Expand Down Expand Up @@ -297,26 +296,27 @@ def test_master_read(self):
self.assertEqual(data, b"")

def test_spawn_doesnt_hang(self):
self.addCleanup(unlink, TESTFN)
with open(TESTFN, 'wb') as f:
STDOUT_FILENO = 1
dup_stdout = os.dup(STDOUT_FILENO)
os.dup2(f.fileno(), STDOUT_FILENO)
buf = b''
def master_read(fd):
nonlocal buf
data = os.read(fd, 1024)
buf += data
return data
# gh-140482: Do the test in a pty.fork() child to avoid messing
# with the interactive test runner's terminal settings.
pid, fd = pty.fork()
if pid == pty.CHILD:
pty.spawn([sys.executable, '-c', 'print("hi there")'])
os._exit(0)

try:
buf = bytearray()
try:
pty.spawn([sys.executable, '-c', 'print("hi there")'],
master_read)
finally:
os.dup2(dup_stdout, STDOUT_FILENO)
os.close(dup_stdout)
self.assertEqual(buf, b'hi there\r\n')
with open(TESTFN, 'rb') as f:
self.assertEqual(f.read(), b'hi there\r\n')
while (data := os.read(fd, 1024)) != b'':
buf.extend(data)
except OSError as e:
if e.errno != errno.EIO:
raise

(pid, status) = os.waitpid(pid, 0)
self.assertEqual(status, 0)
self.assertEqual(buf.take_bytes(), b"hi there\r\n")
finally:
os.close(fd)

class SmallPtyTests(unittest.TestCase):
"""These tests don't spawn children or hang."""
Expand Down
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