Tom Nicholas

Upstream-dev tests are passing. But they all need to pass otherwise these new methods will error on `zarr-python

**These [test failures](https://github.com/pydata/xarray/actions/runs/16880159019/job/47813839254?pr=10327#step:10:3623) are actually non-deterministic.** The test tries to do vectorized indexing, and expects an error about vectorized indexing not being supported to be raised. But the test sometimes...

> the decision on whether or not to use basic, orthogonal, or vectorized indexing depends on the types of indexers you pass to. I'm passing exactly the same indexers every...

> changing my test to be happy with either error As I thought, with this change applied (in https://github.com/pydata/xarray/pull/10327/commits/a7918e4f82aa7972bb448dcbf4110c14a1c0e930) now everything seems to be passing. (I don't think the warnings...

> I think I figured out why: `create_test_data` creates a dataset that has three data variables, two of which do not have both indexed dims. Thus, if these variables are...

> It would be good to wire this up to test_backends somehow, even if just for a few indexing + roundtrip tests. Do you see a path there @dcherian I...

> Try to consolidate indexing tests with those in `test_variable.py`, potentially by defining a subclass of `Variable` that only implements async methods @dcherian I tried to implement this suggestion of...

I also removed `test_async.py` in favour of moving those tests (which are all zarr-dependent) into `test_backends.py`.

Thanks for raising this, this isn't the first time that the issue of an argument being named `dim` when it should really be `coord` has come up, see https://github.com/pydata/xarray/pull/3993 for...

> I wrote some tutorial material here: I was looking for that one! The content on that really fills a much-needed gap (and is really good). I think a dedicated...