Bug Report

Regression tests intermittently fail on their first GitHub Actions run but pass when the workflow is rerun. They also pass consistently when run locally.

The failures appear to be caused by regression tests running in parallel with pytest-xdist while sharing the same .testdata directory.

To Reproduce

rm -rf .testdata
pytest tests/regression --run-slow -n auto

Actual output

One or more regression tests fail. Rerunning the workflow generally passes without any code changes.

Expected output

The regression tests should pass consistently on the first run.

Additional Context

The tests now run quickly enough without parallel execution. The proposed fix is to remove the pytest-xdist implementation and run the regression tests serially.