NestedDirectoryStore.listdir returns invalid chunk keys

[braingram]

Zarr version

2.13.6 and current head 0bf0b3b

Numcodecs version

0.11.0

Python Version

3.10.6

Operating System

Mac

Installation

pip install zarr and built from source

Description

Calling listdir on NestedDirectoryStore returns keys with a '.' dimension separator even though the store does not support this separator.

I believe the issue is this line:

zarr-python/zarr/storage.py

Line 1207 in 0bf0b3b

new_children.append(rel_path.replace(os.path.sep, '.'))

I will open a PR with a fix and update to the tests.

Steps to reproduce

import zarr

store = zarr.storage.NestedDirectoryStore('tmp')
z = zarr.zeros((10, 10), chunks=(5, 5), store=store)
z[:] = 1
keys = zarr.storage.listdir(store)
print(f"Store keys: {keys}")

Returns

Store keys: ['.zarray', '0.0', '0.1', '1.0', '1.1']

However attempts to get data for those keys returns None:

print(store.get('0.0'))

Returns

None

Additional output

No response