add regression workflow

[antbern]

An attempt to create a CI workflow that can do some kind of regression test and compare the generate output map from the PR branch with the output of the master branch 🚀

Steps:

1. Download a LAZ input file for use for the regressions. I personally uploaded a file to google drive and stored the download link in the REGRESSION_LAZ_FILE_URL secret. You will need to do something similar to make this work.
2. Compile and run the program on the PR branch.
3. Checkout the master branch.
4. Compile and run the program on the master branch.
5. Download, extract and run the binary from the latest release.
6. Compare the generated output map files. I tried using imagemagick but it has some memory limits when running in the GitHub runners, so in the end I ended up with pngcomp which checks pixel-by-pixel and outputs some metrics.
7. Upload the metrics and generated files as artifacts (in case one want to inspect the files)
8. Check if some metric is below threshold for acceptance and fail the job if change is too big. Currently set to fail if there is not a 100% overlap between the two maps.

What do you think? 🤔

[rphlo]

Could we use latest binary from release?

[antbern]

That should be doable yes. It depends on what should be tested: the latest release vs the current new features (PR branch), or the latest features (possibly unreleased) against the new features (PR branch) 🤔

[rphlo]

Let's test against latest release if possible, what is in master might not always be clean.
Also I am thinking it may help the test execution time if we do not have to compile.

[antbern]

Changed in 3badd60, see a successful workflow run here: https://github.com/antbern/rusty-pullauta/actions/runs/10808286676

I also added the output as a job summary which can also be seen in the link above 🚀

[rphlo]

Do you mind sharing the LAZ file you used in your test, I'll host it somewhere...

[antbern]

Sure, here is a link. It is from Lantmäteriet and provided without license (CC0) so should be fine to host publicly 💯 It's about 180Mb and covers a 2,5km² area.

Perhaps there are better files with more varied terrain etc. Should probably also add a test that processes multiple files at some point...

[rphlo]

"""With the exception of GITHUB_TOKEN, secrets are not passed to the runner when a workflow is triggered from a forked repository.""" Let's use a variable instead.
preference for name like KP_TEST_LAZ_URL