Surprising N5FSStore test failure

[joshmoore]

Using the Python 3.9 / Debian sid Dockerfile in zarr-developers/zarr-python#858 and checking out the master branch, zarr/tests/test_core.py::TestArrayWithN5FSStore::test_nchunks_initialized fails as below. This is not the case for the Python 3.9 build in GHA.

cc: @d-v-b

zarr/tests/test_core.py:1811:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
zarr/core.py:1280: in __setitem__
    self.set_basic_selection(pure_selection, value, fields=fields)
zarr/core.py:1375: in set_basic_selection
    return self._set_basic_selection_nd(selection, value, fields=fields)
zarr/core.py:1675: in _set_basic_selection_nd
    self._set_selection(indexer, value, fields=fields)
zarr/core.py:1747: in _set_selection
    self._chunk_setitems(lchunk_coords, lchunk_selection, chunk_values,
zarr/core.py:1941: in _chunk_setitems
    self._chunk_delitems(empty_chunks.keys())
zarr/core.py:1950: in _chunk_delitems
    self.store.delitems(ckeys)
zarr/storage.py:1211: in delitems
    self.map.delitems(nkeys)
/usr/lib/python3/dist-packages/fsspec/mapping.py:114: in delitems
    self.fs.rm([self._key_to_str(k) for k in keys])
/usr/lib/python3/dist-packages/fsspec/implementations/local.py:105: in rm
    path = self._strip_protocol(path).rstrip("/")
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

cls = <class 'fsspec.implementations.local.LocalFileSystem'>, path = ['/tmp/tmpwvl8yc5e/1', '/tmp/tmpwvl8yc5e/2', '/tmp/tmpwvl8yc5e/3', '/tmp/tmpwvl8yc5e/4', '/tmp/tmpwvl8yc5e/5', '/tmp/tmpwvl8yc5e/6', ...]

    @classmethod
    def _strip_protocol(cls, path):
        path = stringify_path(path)
>       if path.startswith("file://"):
E       AttributeError: 'list' object has no attribute 'startswith'

/usr/lib/python3/dist-packages/fsspec/implementations/local.py:145: AttributeError
================================================================================================================= warnings summary =================================================================================================================
zarr/tests/test_creation.py: 1 warning
zarr/tests/test_storage.py: 14 warnings
  /tmp/zarr-python/zarr/n5.py:706: RuntimeWarning: Not all N5 implementations support blosc compression (yet). You might not be able to open the dataset with another N5 library.
    warnings.warn(

zarr/tests/test_indexing.py::test_slice_selection_uints
  /tmp/zarr-python/zarr/tests/test_indexing.py:1444: FutureWarning: Using a non-tuple sequence for multidimensional indexing is deprecated; use `arr[tuple(seq)]` instead of `arr[seq]`. In the future this will be interpreted as an array index, `arr[np.array(seq)]`, which will result either in an error or a different result.
    assert arr[slice_sel].shape == (1, 6)

-- Docs: https://docs.pytest.org/en/stable/warnings.html
=============================================================================================================== slowest 10 durations ===============================================================================================================
11.99s call     zarr/tests/test_indexing.py::test_set_orthogonal_selection_3d
3.83s call     zarr/tests/test_core.py::TestArrayWithFSStorePartialRead::test_non_cont
1.97s call     zarr/tests/test_indexing.py::test_set_orthogonal_selection_2d
1.32s call     zarr/tests/test_core.py::TestArrayWithFSStorePartialRead::test_array_2d
0.89s call     zarr/tests/test_storage.py::test_format_compatibility
0.85s call     zarr/tests/test_indexing.py::test_get_orthogonal_selection_3d
0.81s call     zarr/tests/test_core.py::TestArrayWithSQLiteStore::test_iter
0.78s call     zarr/tests/test_core.py::TestArrayWithFSStoreNestedPartialRead::test_array_2d
0.76s call     zarr/tests/test_core.py::TestArrayWithSQLiteStore::test_islice
0.73s call     zarr/tests/test_core.py::TestArrayWithFSStoreNestedPartialRead::test_non_cont
============================================================================================================= short test summary info ==============================================================================================================
FAILED zarr/tests/test_core.py::TestArrayWithN5FSStore::test_nchunks_initialized - AttributeError: 'list' object has no attribute 'startswith'
================================================================================== 1 failed, 2176 passed, 453 skipped, 8 xfailed, 16 warnings in 82.69s (0:01:22) ==================================================================================

[d-v-b]

Interesting! Something is a list when it shouldn't be... I can dig in :)

[d-v-b]

I transferred this issue from zarr-python to n5py.