🐛 Fix obstore listdir method using _relativize_path (#3657)

* 🐛 Fix obstore listdir method using _relativize_path

* 📝 Add changelog entry

* its a bugfix

---------

Co-authored-by: Davis Bennett <davis.v.bennett@gmail.com>

Author: antoinegaston

changes/3657.bugfix.md

@@ -0,0 +1 @@
+Fix obstore _transform_list_dir implementation to correctly relativize paths (removing lstrip usage).

src/zarr/storage/_obstore.py

@@ -4,6 +4,8 @@
 import contextlib
 import pickle
 from collections import defaultdict
+from itertools import chain
+from operator import itemgetter
 from typing import TYPE_CHECKING, Generic, Self, TypedDict, TypeVar
 
 from zarr.abc.store import (
@@ -15,6 +17,7 @@
 )
 from zarr.core.common import concurrent_map
 from zarr.core.config import config
+from zarr.storage._utils import _relativize_path
 
 if TYPE_CHECKING:
     from collections.abc import AsyncGenerator, Coroutine, Iterable, Sequence
@@ -263,10 +266,11 @@ async def _transform_list_dir(
     # We assume that the underlying object-store implementation correctly handles the
     # prefix, so we don't double-check that the returned results actually start with the
     # given prefix.
-    prefixes = [obj.lstrip(prefix).lstrip("/") for obj in list_result["common_prefixes"]]
-    objects = [obj["path"].removeprefix(prefix).lstrip("/") for obj in list_result["objects"]]
-    for item in prefixes + objects:
-        yield item
+    prefix = prefix.rstrip("/")
+    for path in chain(
+        list_result["common_prefixes"], map(itemgetter("path"), list_result["objects"])
+    ):
+        yield _relativize_path(path=path, prefix=prefix)
 
 
 class _BoundedRequest(TypedDict):

src/zarr/testing/store.py

@@ -492,24 +492,36 @@ async def test_list_empty_path(self, store: S) -> None:
         assert observed_prefix_sorted == expected_prefix_sorted
 
     async def test_list_dir(self, store: S) -> None:
-        root = "foo"
-        store_dict = {
-            root + "/zarr.json": self.buffer_cls.from_bytes(b"bar"),
-            root + "/c/1": self.buffer_cls.from_bytes(b"\x01"),
-        }
+        roots_and_keys: list[tuple[str, dict[str, Buffer]]] = [
+            (
+                "foo",
+                {
+                    "foo/zarr.json": self.buffer_cls.from_bytes(b"bar"),
+                    "foo/c/1": self.buffer_cls.from_bytes(b"\x01"),
+                },
+            ),
+            (
+                "foo/bar",
+                {
+                    "foo/bar/foobar_first_child": self.buffer_cls.from_bytes(b"1"),
+                    "foo/bar/foobar_second_child/zarr.json": self.buffer_cls.from_bytes(b"2"),
+                },
+            ),
+        ]
 
         assert await _collect_aiterator(store.list_dir("")) == ()
-        assert await _collect_aiterator(store.list_dir(root)) == ()
 
-        await store._set_many(store_dict.items())
+        for root, store_dict in roots_and_keys:
+            assert await _collect_aiterator(store.list_dir(root)) == ()
 
-        keys_observed = await _collect_aiterator(store.list_dir(root))
-        keys_expected = {k.removeprefix(root + "/").split("/")[0] for k in store_dict}
+            await store._set_many(store_dict.items())
 
-        assert sorted(keys_observed) == sorted(keys_expected)
+            keys_observed = await _collect_aiterator(store.list_dir(root))
+            keys_expected = {k.removeprefix(root + "/").split("/")[0] for k in store_dict}
+            assert sorted(keys_observed) == sorted(keys_expected)
 
-        keys_observed = await _collect_aiterator(store.list_dir(root + "/"))
-        assert sorted(keys_expected) == sorted(keys_observed)
+            keys_observed = await _collect_aiterator(store.list_dir(root + "/"))
+            assert sorted(keys_expected) == sorted(keys_observed)
 
     async def test_set_if_not_exists(self, store: S) -> None:
         key = "k"