Confusion about the dimension_separator keyword

I don’t really understand how to use the new dimension_separator keyword, in particular:

1. Creating a DirectoryStore(dimension_separator="/") does not have the effect I would expect (see code and problem description below).
2. Why does zarr still have the NestedDirectoryStore? Shouldn’t it be the same as DirectoryStore(dimension_separator="/")? Hence I would assume that NestedDirectoryStore could either be removed or (if to be kept for legacy purposes) should just map to DirectoryStore(dimension_seperator="/").

Minimal, reproducible code sample, a copy-pastable example if possible

import zarr
store = zarr.DirectoryStore("test.zarr", dimension_separator="/")
g = zarr.open(store, mode="a")
ds = g.create_dataset("test", shape=(10, 10, 10))
ds[:] = 1

Problem description

Now, I would assume that the chunks are nested, but I get:

$ ls test.zarr/test
0.0.0

but to, to my confusion, also this:

$ cat test.zarr/test/.zarray
...
"dimension_separator": "/",
...

If I use NestedDirectoryStore instead, the chunks are nested as expected.

Version and installation information

Please provide the following:

• Value of zarr.__version__: 2.8.3
• Value of numcodecs.__version__: 0.7.3
• Version of Python interpreter: 3.8.6
• Operating system: Linux
• How Zarr was installed: using conda

[joshmoore]

After a lengthy back and forth, I think this is a last call for opinions on the fix. I’d propose to get it out in 2.9.0 (noting that that also drops support for Python 3.6)

[thewtex]

Another +1 and thanks to @joshmoore for #773, which addressed the behavior I observed when trying to use DirectoryStore and dimension_separator='/' with zarr and xarray.

Are there plans to integrate #773?