Ensure that files our tests depend on are preserved
I doubt this is much of an issue but for the sake of safety it might be good if we had somewhere to store root files used in tests (such as https://gitlab.cern.ch/lhcb-dpa/analysis-productions/lbapcommon/-/blob/master/tests/checks/test_simple.py#L24) to ensure that we have control over them and prevent the tests from failing one day because someone else deleted a file we happen to test on.
Maybe they can just be stored in the repository like https://gitlab.cern.ch/lhcb-dpa/analysis-productions/lbapcommon/-/blob/master/tests/checks/example_tuple_with_lumi.root but that's probably not ideal depending on how large they are.