Importing idlelib.run deletes tkinter dialog submodules from sys.modules

[serhiy-storchaka]

Bug report

idlelib/run.py scrubs tkinter at import time (bpo-25507, gh-59396):

for mod in ('simpledialog', 'messagebox', 'font', 'dialog', 'filedialog', 'commondialog', 'ttk'):
    try:
        delattr(tkinter, mod)
        del sys.modules['tkinter.' + mod]
    except (AttributeError, KeyError):
        pass

test_run.py does from idlelib import run, so running it evicts tkinter.commondialog from sys.modules. A later import re-executes commondialog, creating a second Dialog class.

The common-dialog tests cache the class at load (from tkinter.commondialog import Dialog) and patch it with swap_attr(Dialog, '_test_callback', ...). After the re-import that cached class is stale, so the patch misses the class the live dialog uses, and test_colorchooser.test_askcolor opens the real modal color chooser and hangs:

./python -m test -uall test_tkinter test_ttk test_idle

It only fails when test_run runs before the dialog test in the same process (not under -j).

Importing a module shouldn't mutate global sys.modules; idlelib.run should do the scrub only when launched as the subprocess main, not at import.

Linked PRs

• gh-156896: Stop scrubbing tkinker submodules upon idlelib.run import #156915
• [3.15] gh-156896: Stop scrubbing tkinter submodules upon idlelib.run import (GH-156915) #156958
• [3.14] gh-156896: Stop scrubbing tkinter submodules upon idlelib.run import (GH-156915) #156959
• [3.13] gh-156896: Stop scrubbing tkinter submodules upon idlelib.run import (GH-156915) #156960

[terryjreedy]

I agree. The purpose is to prevent user code running from IDLE passing when it should fail due to missing tkinter submodule imports. I will add the needed clause to the existing if guard.

[terryjreedy]

Module run is not launched as subprocess main. It is imported with __import__('idlelib.run'), avoiding binding it in main. (Function run.main is run by appending .run.main() to the import.) So I 'guarded' the scrubbing by wrapping it in a function called at the top of main.