Fix shell_magic load failure on Windows by lazy-initializing shell process#364
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blink1073 merged 2 commits intoCalysto:mainfrom Mar 13, 2026
Merged
Fix shell_magic load failure on Windows by lazy-initializing shell process#364blink1073 merged 2 commits intoCalysto:mainfrom
blink1073 merged 2 commits intoCalysto:mainfrom
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…ndows Previously, ShellMagic.__init__ eagerly called start_process(), which launched powershell immediately on Windows. On some systems (e.g. Windows 7), the pexpect prompt detection timed out, raising an exception that propagated up through register_magics() and caused reload_magics() to log a spurious "Can't load shell_magic.py" error — preventing the magic from loading at all. The fix defers process startup to the first call to eval(), so shell_magic.py loads cleanly and any startup errors only surface when %shell is actually used. Closes Calysto#247
_make_kernel_with_parent created a ZMQ PUB socket but never closed it, unlike get_kernel() which uses weakref.finalize. The open sockets were GC'd during later tests, causing ResourceWarning → PytestUnraisableExceptionWarning failures when the full test suite ran.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #364 +/- ##
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Coverage 90.95% 90.95%
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Files 51 51
Lines 2874 2875 +1
Branches 402 403 +1
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+ Hits 2614 2615 +1
Misses 181 181
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Closes #247
Summary
ShellMagic.__init__was eagerly callingstart_process(), which on Windows immediately tried to spawn a powershell process via pexpectpexpect.TIMEOUTexceptionregister_magics()toreload_magics(), which logged a spurious"Can't load shell_magic.py"error and left the magic unregisteredstart_process()call from__init__and add lazy initialization ineval()— the process is now started on first useTest plan
tests/magics/test_shell_magic.pytests all pass (verified locally)python -m octave_kernel.check(or any MetaKernel-based kernel check) no longer shows the "Can't load shell_magic.py" error%shell/!commands still work normally when invoked