Create Downgrade.yml

[JoshuaLampert]

Similar to SciML/SciMLBase.jl#553.

See https://github.com/cjdoris/julia-downgrade-compat-action and also trixi-framework/Trixi.jl#1771.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (21de330) 17.64% compared to head (eb28109) 17.64%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #105   +/-   ##
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  Coverage   17.64%   17.64%           
=======================================
  Files           3        3           
  Lines        1423     1423           
=======================================
  Hits          251      251           
  Misses       1172     1172           

Flag	Coverage Δ
unittests	17.64% <ø> (ø)

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[JoshuaLampert]

There is a bug in the GitHub action that lets the action fail if a package name contains an underscore (here P4est_jll), see cjdoris/julia-downgrade-compat-action#2.

[JoshuaLampert]

The GitHub action is fixed now and in principle it works with the newest version. I've set the lower compat bounds to the lowest possible such that after downgrading the tests still pass.
However, it seems that - uses: cjdoris/julia-downgrade-compat-action@v1 doesn't recognize the newest version v1.0.7 of the GitHub action although it's already released. Explicitly stating - uses: cjdoris/julia-downgrade-compat-action@v1.0.7 fixes the version, but I'd rather not like to specify the exact version. Usually, @v1 should take the latest release, shouldn't it @ranocha?

[ranocha]

Looks like GitHub is doing weird stuff here, see https://devopsjournal.io/blog/2022/10/19/How-GitHub-Actions-versioning-works

The @vXYZ specification makes it look at a tag vXYZ in the repo. The tag v1 in the repo points to an old version, see https://github.com/cjdoris/julia-downgrade-compat-action/tags
The maintainer has to update the tag manually to make it work as you (and I) would expect. Thus, it's fine to use julia-downgrade-compat-action@v1.0.7 explicitly.

[JoshuaLampert]

Ok, I set the version back to v1.0.7.

[ranocha]

Thanks!