# What changed in pyfakefs

> 5 changes in pyfakefs 6 from its official release notes, upgrade guides and advisories. Each one cited. Sources checked 2026-10-25. HTML: https://unstale.sh/pypi/pyfakefs/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## pyfakefs 6

### Fixes and other changes

- Fake file wrappers now derive from io.TextIOBase or io.BufferedIOBase, so isinstance checks for these classes succeed. (6.2.0) — [release notes](https://github.com/pytest-dev/pyfakefs/releases/tag/v6.2.0)
- Case sensitivity is now correctly set for fake posix paths in hash(), Path.match and Path.full_match. (6.2.0) — [release notes](https://github.com/pytest-dev/pyfakefs/releases/tag/v6.2.0)
- Some pseudo-devices are routed to the system instead of being patched, ensuring os.urandom and related functions work correctly with PyPy. (6.2.0) — [release notes](https://github.com/pytest-dev/pyfakefs/releases/tag/v6.2.0)
- The fake file seek method now returns the location in the file. (6.2.0) — [release notes](https://github.com/pytest-dev/pyfakefs/releases/tag/v6.2.0)
- Fixes a Windows-specific issue with os.path.realpath. (6.1.5) — [release notes](https://github.com/pytest-dev/pyfakefs/releases/tag/v6.1.5)