rich is not a dependency of zarr but is required by zarr.Group.tree() function

[flyingfalling]

Zarr version

3.0.6

Numcodecs version

0.15.1

Python Version

3.13

Operating System

Linux

Installation

pip install zarr

Description

rich is not a dependency of zarr but is required by zarr.Group.tree() function

The following code raises an exception (due to "import rich" in tree()) despite being minimal example:

Here is the full traceback:

root.tree()

Traceback (most recent call last):
  File "/home/riveale/zarrvenv/lib64/python3.13/site-packages/zarr/core/_tree.py", line 9, in <module>
    import rich
ModuleNotFoundError: No module named 'rich'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<python-input-2>", line 1, in <module>
    root.tree()
    ~~~~~~~~~^^
  File "/home/riveale/zarrvenv/lib64/python3.13/site-packages/zarr/core/group.py", line 2300, in tree
    return self._sync(self._async_group.tree(expand=expand, level=level))
           ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/riveale/zarrvenv/lib64/python3.13/site-packages/zarr/core/sync.py", line 208, in _sync
    return sync(
        coroutine,
        timeout=config.get("async.timeout"),
    )
  File "/home/riveale/zarrvenv/lib64/python3.13/site-packages/zarr/core/sync.py", line 163, in sync
    raise return_result
  File "/home/riveale/zarrvenv/lib64/python3.13/site-packages/zarr/core/sync.py", line 119, in _runner
    return await coro
           ^^^^^^^^^^
  File "/home/riveale/zarrvenv/lib64/python3.13/site-packages/zarr/core/group.py", line 1550, in tree
    from zarr.core._tree import group_tree_async
  File "/home/riveale/zarrvenv/lib64/python3.13/site-packages/zarr/core/_tree.py", line 13, in <module>
    raise ImportError("'rich' is required for Group.tree") from e
ImportError: 'rich' is required for Group.tree

Steps to reproduce

import zarr;

root = zarr.create_group(store='test.zarr');

root.tree();

Additional output

No response

[d-v-b]

rich is an optional dependency, and you can install it with zarr with pip install zarr[optional], but this is not at all intuitive. we should probably come up with a better name for this, and update that import error

[d-v-b]

looks like this has been discussed in the past:
#2539
#2541

[flyingfalling]

@d-v-b Hey I was just preparing a pull request and I noticed that it is in the [test] and [optional] in the .toml et cetera. Yea...not much to do about this if you don't want to pull it for normal installations. I don't know the right pythontic way to deal with this kind of thing.

[flyingfalling]

Anyways, thanks for pointing to the old issues. It seems this is "expected behavior", so I will close it.