Gitlab.com CI - simulate hardware for testing

I would like to test some code that relies on the presence of hardware. Specifically, one or more S.M.A.R.T. capable harddrives that are interogated via smartmontools.
In the gitlab.com CI, the runners (obviously) have no harddisks attached.

What would be a good way to simulate the presence of a harddisk so that I could then test the software?