It would be nice to just be able to run cargo test, rather than needing to set the env var. To do this we need to make our tests thread safe, which means we can't have any state on disk or in the OS. In particular, we can't set the current directory, which the RLS currently relies on.

We could pas a path to the RLS, rather than relying on the current directory, but that might mean skipping testing of some elements.

I'm putting this on the beta milestone because I don't think it should block alpha2, but it would be nice to fix this sooner rather than later.