dynix/tests

Notes for running the tests

The VM tests do Nix builds inside the VMs, so they have writable Nix stores. Writable Nix stores in NixOS VM tests are, by default, tmpfs, but to speed up IO for the in-VM nixos-rebuilds, ./module-allow-rebuild-in-vm.nix instead sets virtualisation.writableStoreUseTmpfs = false;, and allocates a much larger root filesystem for the VM. Specifically, each VM test allocates 20 GiB. If you are running low on disk space, disable virtualisation.writableStoreUseTmpfs in ./module-allow-rebuild-in-vm.