CI: can_fast_ci_build.py unittests fix

[kaspar030]

Contribution description

This PR should fix #18987.

I first started with some sophisticated regex based generic replacement / mapping functionality, then decided to go simple...

The issue is that can_fast_ci_run.py correctly classifies any change to tests/unittests/tests-$foo to be a change to that module, but unittests are special in our build system - they can be built as one huge binary (tests/unittests), or individually (tests/unittests/tests-*). The latter are not built by CI and are not listed when doing make info-applications.

Testing procedure

Issues/PRs references

Fixes #18987.

[riot-ci]

Murdock results

✔️ PASSED

34cfdac ci/can_fast_ci_run.py: add workaround for #18987

Success	Failures	Total	Runtime
1	0	1	54s

Artifacts

• Documentation preview

[MrKevinWeiss]

Please squash and remove the extra commits then I think it is good. ACK.

[miri64]

Ah more general approach could be to find the parent directory that has a Makefile [edit]with an APPLICATION defined[/edit].

[maribu]

The tests don't define an application name, but rather include a Makefile that sets it based on the folder name.

One could try to go up the tree further and not find the closed related parent dir having a Makefile (as done now), but rather the most distant related parent folder.

But I think that unit tests a really just a special case. I think it is fine to habe a special case for it in the code.

And more generally: I wonder if it wouldn't have made more sense to just have multiple applications for the unit tests. Right now, adding more test cases always runs into the risk of reducing the number of boards with enough memory further. If we do this, we no longer need a special case here as well.

[kaspar030]

I wonder if it wouldn't have made more sense to just have multiple applications for the unit tests.

Every tests-foo is already it's own application. We just don't use that in CI (and they're not exposed via "make info-applications".

[MrKevinWeiss]

And more generally: I wonder if it wouldn't have made more sense to just have multiple applications for the unit tests. Right now, adding more test cases always runs into the risk of reducing the number of boards with enough memory further. If we do this, we no longer need a special case here as well.

Then there would be some tradeoff between flash cycles and size, ideally we do some chunking that would cram as many unittest cases in a binary as possible... But that would require some amount of smarts to implement.