I recently worked on PR #743, which implements issue #440 in the preCICE tutorials repository. Here’s a short recap of what I learned , hope this helps ==>
i spent time on tutorials system tests running full coupled simulations with different solver combinations (e.g. OpenFOAM + CalculiX) and compare results to reference data. That helps catch regressions across the ecosystem when dependencies or adapters change.
The change adds archiving and hash comparison for precice-*-iterations.log from implicit coupling runs. These logs record iterations per time window; if something changes in the coupling scheme or acceleration, iteration counts can shift even when final fields still pass fieldcompare. Comparing hashes of these logs lets us detect that kind of regression.
while working i learned more about the systemtest harness: how Systemtest.py runs build → run → fieldcompare, how reference data is generated and stored in tars, and how CI triggers these tests. The implementation uses a sidecar .iterations-hashes.json so we stay backwards compatible and can extend it (to other files later.)
This should be useful for the upcoming system tests GSoC project–>better iteration-log checks mean we catch coupling changes earlier and make CI more reliable as we add more tests.