nixpkgs/nixos/tests/zram-generator.nix

import ./make-test-python.nix {
  name = "zram-generator";

  nodes.machine = { ... }: {
    zramSwap = {
      enable = true;
      priority = 10;
      algorithm = "lz4";
      swapDevices = 2;
      memoryPercent = 30;
      memoryMax = 10 * 1024 * 1024;
    };
  };

  testScript = ''
    machine.wait_for_unit("systemd-zram-setup@zram0.service")
    machine.wait_for_unit("systemd-zram-setup@zram1.service")
    zram = machine.succeed("zramctl --noheadings --raw")
    swap = machine.succeed("swapon --show --noheadings")
    for i in range(2):
        assert f"/dev/zram{i} lz4 10M" in zram
        assert f"/dev/zram{i} partition  10M" in swap
  '';
}