gh-145821: properly raise OptionError in Option._check_callback when callback_kwargs is invalid

[stefanzetzsche]

Issue

Option._check_callback formats its error message with %r % self.callback_kwargs. When callback_kwargs is a tuple, Python's % operator unpacks it as multiple arguments, causing TypeError instead of the expected OptionError.

Reproducer

from optparse import Option
Option('--foo', action='callback', callback=lambda *a: None, callback_kwargs=(1, 2))
# TypeError: not all arguments converted during string formatting
# Expected: OptionError

Fix

In Lib/optparse.py, wrap the value in a tuple for the format call:

% (self.callback_kwargs,), self)

Tests

Added test_callback_kwargs_tuple_not_dict to TestOptionChecks in Lib/test/test_optparse.py.

• Issue: optparse Option._check_callback raises TypeError instead of OptionError for tuple callback_kwargs #145821

[picnixz]

Please add a regression test.

[bedevere-app]

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[python-cla-bot]

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[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[picnixz]

Don't you also have the same issue when supplying a tuple for a non-callback action? (L713)

[picnixz]

An alterantive would be to use an f-string so that we don't have this issue anymore.

.