How to test a new FileSystem implementation?

[NotSpecial]

Hi, I've been using sshfs recently and it seems to work great with UPath.
However, UPath raises a warning as sshfs has not been tested to work with it.
And I think that's fair. While the basic stuff I've been doing works great, I think it would be good to ensure that all functionality is working.

I'd love to help address this and would appreciate some guidance.
Concretely, I have two questions:

• Are there instructions anywhere how to set up a file system to be tested?
• sshfs is an optional dependency. That means I would have to put it into setup.cfg under [options.extras_require] at dev = , is that correct?

[ap--]

So the simplest way of getting started is:

Add a simple custom implementation:

# upath/implementations/ssh.py
from upath.core import UPath

class SSHPath(UPath):
    pass

register that implementation:

# add to known_implementations
# https://github.com/fsspec/universal_pathlib/blob/e999d11250942cd7279fe9d699d0afcdba5dd8a6/upath/registry.py#L20

"ssh": "upath.implementations.ssh.SSHPath",

Create upath/tests/implementations/test_ssh.py and add the base tests:

import pytest

from upath import UPath
from upath.implementations.ssh import SSHPath

from ..cases import BaseTests


class TestSSHPath(BaseTests):
    @pytest.fixture(autouse=True)
    def path(self, local_testdir):  # fixme: this might need a fixture to spawn an ssh server for testing
        path = ...  # fixme: create your ssh:// base urlpath for tests
        self.path = UPath(path)
        self.prepare_file_system()

    def test_is_SSHPath(self):
        assert isinstance(self.path, SSHPath)

If tests fail, you can work on fixing them by overriding custom methods in upath.implementations.ssh.SSHPath and/or creating a custom subclassed _FSSpecAccessor in upath.implementations.ssh (see the other implementations on how they do it)

Thanks for wanting to contribute ❤️
And feel free to open a draft PR in case you want me to have a look!

Cheers,
Andreas

[ap--]

And forgot:

sshfs is an optional dependency. That means I would have to put it into setup.cfg under [options.extras_require] at dev = , is that correct?

Yes! That's correct

[NotSpecial]

Thank you for the pointers! I'm unable to work on this for the next 2 or 3 weeks, but I definitely want to give it a go afterwards.

[NotSpecial]

I've started working on this (link to fork). Seems to (mostly) work out of the box, with only 4 tests failing. I may be able to dedicate some more time to it later this week to fix those and then open a PR.