all test_socket.py tests fail with python3.8

[nieder]

On macOS 10.13, all tests from test_socket.py fail when tested using python3.8. python2.7 and python3.4-3.7 pass OK.

All the errors exit with an error similar to:

_______________________________________________________ ExpectTestCase.test_stdin_closed ________________________________________________________

self = <tests.test_expect.ExpectTestCase testMethod=test_stdin_closed>

    def test_stdin_closed(self):
        '''
        Ensure pexpect continues to operate even when stdin is closed
        '''
        class Closed_stdin_proc(multiprocessing.Process):
            def run(self):
                sys.__stdin__.close()
                cat = pexpect.spawn('cat')
                cat.sendeof()
                cat.expect(pexpect.EOF)
    
        proc = Closed_stdin_proc()
>       proc.start()

tests/test_expect.py:584: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/sw/lib/python3.8/multiprocessing/process.py:121: in start
    self._popen = self._Popen(self)
/sw/lib/python3.8/multiprocessing/context.py:224: in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
/sw/lib/python3.8/multiprocessing/context.py:284: in _Popen
    return Popen(process_obj)
/sw/lib/python3.8/multiprocessing/popen_spawn_posix.py:32: in __init__
    super().__init__(process_obj)
/sw/lib/python3.8/multiprocessing/popen_fork.py:19: in __init__
    self._launch(process_obj)
/sw/lib/python3.8/multiprocessing/popen_spawn_posix.py:47: in _launch
    reduction.dump(process_obj, fp)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

obj = <Closed_stdin_proc name='Closed_stdin_proc-1' parent=2647 initial>, file = <_io.BytesIO object at 0x10aa334f0>, protocol = None

    def dump(obj, file, protocol=None):
        '''Replacement for pickle.dump() using ForkingPickler.'''
>       ForkingPickler(file, protocol).dump(obj)
E       AttributeError: Can't pickle local object 'ExpectTestCase.test_stdin_closed.<locals>.Closed_stdin_proc'

/sw/lib/python3.8/multiprocessing/reduction.py:60: AttributeError
------------------------------------------------------------- Captured stdout call --------------------------------------------------------------

 tests.test_expect.ExpectTestCase.test_stdin_closed 

[dmacks]

Likewise on newer pythons (tried py3.10 on OS X 10.13).

[nieder]

--- pexpect/__init__.py-orig	2024-01-20 07:50:39
+++ pexpect/__init__.py	2024-01-20 07:50:43
@@ -70,6 +70,7 @@
 '''
 
 import sys
+import multiprocessing
 PY3 = (sys.version_info[0] >= 3)
 
 from .exceptions import ExceptionPexpect, EOF, TIMEOUT
@@ -81,6 +82,9 @@
     from .pty_spawn import spawn, spawnu
     from .run import run, runu
 
+if sys.platform.startswith('darwin'):
+    multiprocessing.set_start_method('fork')
+
 __version__ = '4.9.0'
 __revision__ = ''
 __all__ = ['ExceptionPexpect', 'EOF', 'TIMEOUT', 'spawn', 'spawnu', 'run', 'runu',

cf kevlened/pytest-parallel#41 . Not sure how safe this actually is, however.

kevlened/pytest-parallel@9c69c4e