Fix Argument.__repr__ crash when _action is not initialized

[EternalRights]

Ran into this while looking at #13817. When Argument.__init__ doesn't complete (e.g. if argparse.Action raises during construction), calling repr() on the partially-initialized Argument triggers a secondary AttributeError because self._action doesn't exist yet. This masks the original error message.

The fix uses getattr(self, "_action", None) in __repr__ and returns "Argument(<uninitialized>)" when _action is missing, as RonnyPfannschmidt suggested. This way the original exception message gets through instead of being buried under a secondary crash.

[nicoddemus]

Why two separate tests for this? Wouldn't make sense to also test the type in test_argument_repr_initialized? For that matter, test_argument_repr_initialized could check the entire string, instead of relying on in checks for a few keywords.

[EternalRights]

Thanks for the review! You're right on all points.

1. I kept test_argument_repr_uninitialized separate because it tests a fundamentally different construction path (bare __new__ vs proper initialization through parser.addoption). This follows the same pattern as test_saferepr.py where error paths are separate from normal ones. However, I agree the initialized and with_type cases should be merged as they test the same construction path.

2. Agreed — the type branch should be tested within test_argument_repr_initialized, not as a separate test. I'll merge them.

3. Agreed — I'll switch to exact string matching with ==. I see test_saferepr.py consistently uses exact comparison.

I'll push the updates shortly.

[nicoddemus]

Awesome, thanks!

[patchback]

Backport to 9.0.x: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 84ae27e on top of patchback/backports/9.0.x/84ae27e4710af45cc307f8c0c25259e917090219/pr-14429

Backporting merged PR #14429 into main

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/pytest-dev/pytest.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/9.0.x/84ae27e4710af45cc307f8c0c25259e917090219/pr-14429 upstream/9.0.x

4. Now, cherry-pick PR Fix Argument.__repr__ crash when _action is not initialized #14429 contents into that branch:

   $ git cherry-pick -x 84ae27e4710af45cc307f8c0c25259e917090219

   If it'll yell at you with something like fatal: Commit 84ae27e4710af45cc307f8c0c25259e917090219 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 84ae27e4710af45cc307f8c0c25259e917090219

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Fix Argument.__repr__ crash when _action is not initialized #14429 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/9.0.x/84ae27e4710af45cc307f8c0c25259e917090219/pr-14429

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

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