[Rodrigo-Palma]

Summary

save() never declared storage_options, so it arrived through **kwargs. In save(), **kwargs are the arrays to write, which caused two separate problems.

First, save(store, arr, storage_options=...) no longer took the single-array branch, because that branch requires len(kwargs) == 0. A lone array was written as a group holding arr_0 instead of as an array.

Second, the option never reached the store, so an fsspec URL was opened without it.

This declares storage_options on both the sync and the async save, forwards it to save_array and save_group, and documents it in the same words the sibling functions use.

One line was also removed from save_group: it forwarded storage_options to the per-array save_array calls for positional arrays only (keyword arrays never got it). By that point store_path has already consumed the options, so forwarding them again makes make_store_path reject them as unused. That is the TypeError in the second test below.

For reviewers

The removal inside save_group is the part worth a second look. Everything else is additive.

Measured on main, both new tests fail:

tests/test_api.py::test_save_storage_options_is_not_an_array
E   assert False                      # the node came back as a Group, not an Array

tests/test_api.py::test_save_group_storage_options_positional_args
E   TypeError: 'storage_options' was provided but unused. 'storage_options' is only
    used when the store is passed as an FSSpec URI string.        (_common.py:471)

On this branch tests/test_api.py is 355 passed, 9 skipped (CuPy not installed), and ruff check, ruff format --check and mypy are clean on the touched files.

Author attestation

• I am a human, these are my changes, and I have reviewed and understood every change and can explain why each is correct.

TODO

• Add unit tests and/or doctests in docstrings
• Add docstrings and API docs for any new/modified user-facing classes and functions
• New/modified features documented in docs/user-guide/*.md (bug fix, no user-guide change)
• Changes documented as a new file in changes/
• GitHub Actions have all passed
• Test coverage is 100% (Codecov passes)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.43%. Comparing base (0ba2ca2) to head (475dff7).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4415   +/-   ##
=======================================
  Coverage   94.43%   94.43%           
=======================================
  Files          93       93           
  Lines       13219    13219           
=======================================
  Hits        12483    12483           
  Misses        736      736           

Files with missing lines	Coverage Δ
src/zarr/api/asynchronous.py	96.32% <100.00%> (ø)
src/zarr/api/synchronous.py	92.95% <100.00%> (ø)

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[d-v-b]

thanks @Rodrigo-Palma