fix: preserve absolute root in _strip_protocol so walk("/") works

sshfs/spec.py

@@ -84,7 +84,14 @@ def __init__(
     def _strip_protocol(cls, path):
         # Remove components such as host and username from path.
         inferred_path = infer_storage_options(path)["path"]
-        return super()._strip_protocol(inferred_path)
+        stripped = super()._strip_protocol(inferred_path)
+        # super() collapses a bare "/" to the (empty) root_marker. Restore it
+        # only when the caller explicitly supplied the absolute root, so that
+        # walk("/") lists from the root while relative paths (and "") still
+        # resolve against the home directory.
+        if not stripped and inferred_path.startswith("/"):
+            return "/"
+        return stripped
 
     @staticmethod
     def _get_kwargs_from_urls(urlpath):

tests/test_sshfs.py

@@ -203,6 +203,48 @@ def test_ls(fs, remote_dir):
     assert dirs == expected
 
 
+def test_walk(fs, remote_dir):
+    fs.mkdir(remote_dir + "/a")
+    fs.mkdir(remote_dir + "/a/b")
+    fs.touch(remote_dir + "/a/f1")
+    fs.touch(remote_dir + "/a/b/f2")
+
+    result = {
+        root: (sorted(dirs), sorted(files))
+        for root, dirs, files in fs.walk(remote_dir + "/a")
+    }
+    assert result == {
+        remote_dir + "/a": (["b"], ["f1"]),
+        remote_dir + "/a/b": ([], ["f2"]),
+    }
+
+
+def test_walk_root(fs):
+    # Regression: SSHFileSystem._strip_protocol("/") used to collapse the
+    # root to "", so walk("/") listed the home directory and yielded
+    # relative paths that were not considered to exist.
+    root, dirs, files = next(iter(fs.walk("/", maxdepth=1, detail=True)))
+    assert root == "/"
+    for info in dirs.values():
+        assert info["name"].startswith("/")
+        assert fs.exists(info["name"])
+
+
+def test_strip_protocol():
+    strip = SSHFileSystem._strip_protocol
+    # An explicit absolute root is preserved so walk("/") lists from the root.
+    assert strip("/") == "/"
+    assert strip("ssh://host/") == "/"
+    # Empty and relative paths still resolve against the home directory
+    # instead of being redirected to the root.
+    assert strip("") == ""
+    assert strip("ssh://host") == ""
+    assert strip("foo/bar") == "foo/bar"
+    # Regular absolute paths are unaffected.
+    assert strip("/foo/bar") == "/foo/bar"
+    assert strip("ssh://host/foo/bar") == "/foo/bar"
+
+
 def test_mkdir(fs, remote_dir):
     fs.mkdir(remote_dir + "dir/")
     assert fs.isdir(remote_dir + "dir/")