You can run tests using nix-build. For example, to run the test login.nix, you just do: $ nix-build '<nixpkgs/nixos/tests/login.nix>' or, if you don’t want to rely on NIX_PATH: $ cd /my/nixpkgs/nixos/tests $ nix-build login.nix … running the VM test script machine: QEMU running (pid 8841) … 6 out of 6 tests succeeded After building/downloading all required dependencies, this will perform a build that starts a QEMU/KVM virtual machine containing a NixOS system. The virtual machine mounts the Nix store of the host; this makes VM creation very fast, as no disk image needs to be created. Afterwards, you can view a pretty-printed log of the test: $ firefox result/log.html