[v3] Files created during tests

[d-v-b]

Running the dimension separator tests in v3 results in a directory called src/fixture being created, which is not the correct thing for a test to be doing. Files generated for testing should be written to temporary directories. We should change test_dim_separator so that it does not write these files.

The files being written come from this fixture. I don't really understand what this fixture is doing, since it takes tmpdir, but contains a branch that ignores tmpdir and tries to write array data to a hard-coded path in the project directory, if that path is empty. It looks like it's trying to reference these files? If those files are static test fixtures, then should we move them to the tests directory, and remove the capacity for the pytest fixture in test_dim_separator.py to overwrite those fixtures?

@joshmoore do you have any ideas here?

[d-v-b]

I found a few more examples of this pattern: https://github.com/search?q=repo%3Azarr-developers%2Fzarr-python+.resolve%28%29&type=code

I feel like if these tests can work with data generated at testing time, then that's preferable to a static fixture, in which case could we replace the logic for locating the project root with a tmpdir fixture?

[joshmoore]

These aren't temporary files. These are the fixture that are expected to exist. They are getting created, more or less to keep conda-forge (and first time fixture developers) happy. There are extended conversations around this on the feedstock. See #1347

[d-v-b]

I'm trying to wrap my head around that issue you linked @joshmoore, maybe I don't understand enough about the conda feedstock process, but why can't we just put these fixture files in the directory with the tests?

[joshmoore]

Because then they need to be present after pip install.

[d-v-b]

and why are they needed after pip installing? Are these files used by something other than the test suite?

[joshmoore]

conda-forge expects all tests to pass when installed "out of tree".

[d-v-b]

but if the fixtures are moved inside the test suite, then aren't they available if and only if the tests are available?

[d-v-b]

we have been running all our tests in v3 out of tree for a while now...

[d-v-b]

@normanrz #1890 resulted in fixture files being accidentally added to src/zarr/fixture, which I think underscores the need to resolve this issue.

To summarize the situation: our test suite generates fixture files, but it does not save them in a temporary directory. To resolve this, I think we need to choose between two options:

• those files are generated during test time and stored in a temporary directory.
• those files are loaded during test time and stored in the test suite as static assets.

I prefer the first option, because clearly the files can be dynamically generated, but I will accept anything short-term that keeps these files from being generated in src/zarr every time we run the test suite. See #1813 for an implementation of the second option.