Vitest does not discover tests in workspaces

[ufr-scf]

Describe the bug

Vitest does not discover test suites in test files located in workspaces. This only happens when the workspace has it's own installation of vitest, i.e. is not referenced as an npm workspace in the root package.json.

Reproduction

https://github.com/ufr-scf/vitest-monorepo-bug

System Info

System:
    OS: Linux 5.15 Debian GNU/Linux 12 (bookworm) 12 (bookworm)
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
    Memory: 4.01 GB / 7.61 GB
    Container: Yes
    Shell: 5.2.15 - /bin/bash
  Binaries:
    Node: 22.5.1 - /usr/local/bin/node
    Yarn: 1.22.22 - /usr/local/bin/yarn
    npm: 10.8.2 - /usr/local/bin/npm
    pnpm: 9.6.0 - /usr/local/share/npm-global/bin/pnpm
  npmPackages:
    vitest: ^2.0.5 => 2.0.5

Used Package Manager

npm

Validations

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• Read the Contributing Guidelines.
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• The provided reproduction is a minimal reproducible example of the bug.