[feritcemkahraman]

What

Allow upload to retain all files when a file input selects a directory via webkitdirectory, even if multiple is absent. Fixes #1292.

Why

A single selected directory can contain multiple files. Previously the upload helper truncated that selection to the first file.

How

Treat a directory input as a multi-file selection; keep the existing single-file limit for ordinary inputs. Check both the property and the attribute because jsdom may not reflect the non-standard property.

Checklist

• Documentation: no public API changes.
• Tests: upload suite passed (20 tests, 4 snapshots); TypeScript validation and ESLint for the changed files passed. The directory-attribute regression failed before the change.
• Ready to be merged

AI assistance: Codex assisted with the implementation and tests.

Browser verification

In Brave on Windows, we manually selected a directory using the native picker on an input with webkitdirectory and without multiple. The browser returned five files. Passing those files to userEvent.upload on a second input with the same attributes retained all five, with matching file names and webkitRelativePath values. The selected directory had no nested folders.

[snowystinger]

No real-browser directory picker was exercised.

Please run this and report back