Fix issue #13817: Fixed AttributeError in Argument.__repr__ when dest attribute is not set.

[thartline35]

Description

Fixes #13817

When an invalid option name is provided to pytest_addoption() (e.g., missing the -- prefix), pytest correctly detects the error but then fails while trying to display the error message. This results in an AttributeError that obscures the original, helpful validation error.

Root Cause

The Argument.__repr__() method unconditionally accesses self.dest, which hasn't been set yet when initialization is interrupted by a validation error in _set_opt_strings().

The Fix

Added a defensive hasattr() check for dest in __repr__, following the same pattern already used for the type and default attributes.

Before

AttributeError: 'Argument' object has no attribute 'dest'

After

ArgumentError: invalid long option string 'shuffle': must start with --, followed by non-dash

Changes

• Modified src/_pytest/config/argparsing.py: Added hasattr() check for dest attribute
• Added comprehensive test cases in testing/test_argparsing_repr_fix.py
• Added changelog entry
• Updated AUTHORS

All tests pass locally.

[RonnyPfannschmidt]

good start, thanks

please use the NOT_SET constant we have for that

[The-Compiler]

I think the tests will need another round of review here. Will follow up with a more detailed review tomorrow, travelling without laptop right now.

My main concerns are:

• They should be wherever existing tests are instead of a new file
• The good case tests are most likely redundant as we have existing tests
• Duplication can probably be reduced a lot via parametrization
• not quite clear why suppressing the deprecation warning and accessing private API is needed, might be fine though, will need to check once back on laptop

[RonnyPfannschmidt]

We should not let self escape via exceptions in init