gh-144259: Fix Windows EOL wrap by syncing real console cursor

[hyongtao-code]

Long log:

Windows VT terminals do not consistently wrap the cursor when a line
exactly fills the terminal width.
Previously we assumed a wrap always happened, which could desynchronize
the logical cursor from the real console cursor and break subsequent
cursor movement.
This change queries the real cursor position and updates posxy
accordingly, and adds regression tests for both wrap and no-wrap cases.

Video with the patch

fix-issue-144259-V2.mp4

Signed-off-by: Yongtao Huang yongtaoh2022@gmail.com

• Issue: Inconsistent display of long multiline pasted content in the REPL #144259

[hyongtao-code]

Thanks for the review! I agree with your point, so I’ve removed the VT-specific references and updated the tests to exercise both VT and legacy console modes.

[chris-eibl]

As you've seen, many Windows tests fail now, because in headless mode GetConsoleScreenBufferInfo() fails with The handle is invalid.

Instead of swallowing the error, maybe introduce something like

_HasWrappedToNextRow(self, y)

Then, we can simply mock this for most of the tests.

And you can also write an explicit test for _HasWrappedToNextRow by mocking the "bare" GetConsoleScreenBufferInfo() just for this one test?

[hyongtao-code]

Thanks for the suggestion — these failed cases were indeed quite tricky. I decided to follow your proposed approach to fix the failing cases.

[hyongtao-code]

Thanks for the review and guidance. With mocks, we can preserve the original logic and avoid hacky workarounds for CI-specific failures.

[hyongtao-code]

Thanks for your patience.

[chris-eibl]

Thanks for your patience and contribution.
This lgtm now and is ready for a core dev review.

[chris-eibl]

#140333 fixes this, too. Both PRs fix both issues for me.
@hyongtao-code + @tanloong: can you verify?

#140333 does not need to call GetConsoleScreenBufferInfo() and looks simpler, but it lacks tests ...

[tanloong]

Yes, I tried and #140333 also fixes #144259. I once added tests to #140333 but failed and reverted. I would like to try adding again.

[hyongtao-code]

Both PRs fix both issues for me.

Oh, thanks! I think both approaches address the issue. Since @tanloong ’s PR is more concise and came earlier, I’ve decided to close my PR.