Add read tests to ensure backwards compatibility

[tmadlener]

BEGINRELEASENOTES

• Download files written with EDM4hep versions for which we promise backwards compatibility and check whether we can still read them correctly.

ENDRELEASENOTES

• Add infrastructure to download files on the fly
• Embed datamodel version into file
  • Requires Add a hook to inject datamodel version information into podio internals AIDASoft/podio#651
  • Requires Add version module that allows to compare versions in python AIDASoft/podio#678 (for checking and future comparisons)
• Needs Make sure that files with the complete datamodel can be read #361
• Placement of input files after podio and EDM4hep tags have been created

[tmadlener]

I have created the necessary directory on eos to upload files and added the CMake infrastructure to fetch them via the ExternalData functionality on the fly here as well. For testing / developing purposes, I have uploaded files that are created with the latest tag of podio and EDM4hep from this PR, we will need to tag EDM4hep again and replace those files to have a really well defined version for those files to make them reproducible. The schema of EDM4hep hasn't changed since v00-99, but the content you get from createEDM4hepFile.py has.

Maybe this PR needs to be split into two parts, to make it possible to create a tag in between, so that the parts with the backwards compatibility can work off of well defined versions.

[tmadlener]

I will upload new files once we have tags for EDM4hep and podio, then the checks should pass. I don't foresee any more code changes now, unless there are comments from reviewing it.

[tmadlener]

I have added newly produced files (from podio and EDM4hep master / main branches), to verify that things work if both are at their current head. After both have been tagged, I will upload files produced with the actually tagged version and update this accordingly.

[tmadlener]

Input files from tagged podio and EDM4hep have been uploaded and are now used for the tests. The old files from intermediate testing have been removed again.

[tmadlener]

Following this comment, I have added -p no:gaudi_fixtures to the pytest.ini. That stops the pollution of the output with the complete python file that was used for testing. That also makes it possible to keep the normal FAIL_REGULAR_EXPRESSION.

Unless someone wants to still have a look and comment, I would merge this either later today or early tomorrow.

[hegner]

@tmadlener - what's the issue with the failing test on the downstream-build ?

[tmadlener]

That seems to be an unrelated test failure in k4SimDelphes. Looks like it has been failing there as well. I will have a look.