nixpkgs/nixos/tests/snapper.nix

import ./make-test-python.nix ({ ... }:
{
  name = "snapper";

  nodes.machine = { pkgs, lib, ... }: {
    boot.initrd.postDeviceCommands = ''
      ${pkgs.btrfs-progs}/bin/mkfs.btrfs -f -L aux /dev/vdb
    '';

    virtualisation.emptyDiskImages = [ 4096 ];

    virtualisation.fileSystems = {
      "/home" = {
        device = "/dev/disk/by-label/aux";
        fsType = "btrfs";
      };
    };
    services.snapper.configs.home.SUBVOLUME = "/home";
    services.snapper.filters = "/nix";
  };

  testScript = { nodes, ... }: let
    inherit (nodes.machine.services.snapper) snapshotRootOnBoot;
  in ''
    machine.succeed("btrfs subvolume create /home/.snapshots")
    machine.succeed("snapper -c home list")
    machine.succeed("snapper -c home create --description empty")
    machine.succeed("echo test > /home/file")
    machine.succeed("snapper -c home create --description file")
    machine.succeed("snapper -c home status 1..2")
    machine.succeed("snapper -c home undochange 1..2")
    machine.fail("ls /home/file")
    machine.succeed("snapper -c home delete 2")
    machine.succeed("systemctl --wait start snapper-timeline.service")
    machine.succeed("systemctl --wait start snapper-cleanup.service")
    machine.${if snapshotRootOnBoot then "succeed" else "fail"}("systemctl cat snapper-boot.service")
  '';
})