Composer (Dev): Add `cmikey179/vfsstream` and for ILIAS 12

[fhelfer]

This PR suggests adding mikey179/vfsstream (v. 1.6) as composer dependency.

General Information:

• [X] this dependency was already used in ILIAS.
• [X] License: BSD

Usage:

• Used when executing the ILIAS unit test suite.

Wrapped By:

• Not applicable

Reasoning:

• vfsStream is a stream wrapper for a virtual file system that may be helpful in unit tests to mock the real file system.

Maintenance:

• There is not much development activity (see: https://github.com/bovigo/vfsStream/graphs/commit-activity), so it might occur that there will be issues with upcoming PHP versions.
• The risk of relying on this library is small. It is a development dependency, and only a small number of unit tests rely on a mocked file system. If more and more components in ILIAS use the IRSS, the usage of PHP filesystem functions will decrease accordingly, so the corresponding unit tests might get obsolete.

Links:

• Packagist: https://packagist.org/packages/mikey179/vfsstream
• GitHub: https://github.com/bovigo/vfsStream
• Documentation: https://github.com/bovigo/vfsStream/wiki

[matthiaskunkel]

Jour Fixe, 08 DEC 2025: Dependency is accepted for ILIAS 12. Similar PR10659 can be closed.