No test suite found in file on Windows again

Describe the bug

Hi,

I've found a regression regarding this fix.

Certain applications might launch processes with current working directory with lowercased drive letter (e.g. c:\ instead of C:\).

This breaks vitest, it can't find any test (No test suite found in file).

fs.promises.realpath() fixes drive casing (e.g. c:\ becomes C:\), but fs.realpath() does not.

Reproduction

How to reproduce:

• Open command prompt (cmd.exe)
• Run cd c:\path_to_dir_with_tests (note the lowercased c:)
• Run vitest

System Info

vitest/4.0.18 win32-x64 node-v24.13.0

Used Package Manager

yarn

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

Start by reproducing the failure from cmd.exe with a lowercased drive letter, as described, and trace the test-discovery path that uses fs.realpath(). Compare it with fs.promises.realpath(); done means Vitest discovers and runs the tests from that Windows working directory again, with a regression test covering the case.