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")
      '';
  }
)