nixos/tests: add hibernation test

nixos/release.nix

···
   tests.gnome3 = callTest tests/gnome3.nix {};
   tests.gnome3-gdm = callTest tests/gnome3-gdm.nix {};
   tests.grsecurity = callTest tests/grsecurity.nix {};
+  tests.hibernate = callTest tests/hibernate.nix {};
   tests.i3wm = callTest tests/i3wm.nix {};
   tests.installer = callSubTests tests/installer.nix {};
   tests.influxdb = callTest tests/influxdb.nix {};

nixos/tests/hibernate.nix

···
+# Test whether hibernation from partition works.
+
+import ./make-test.nix (pkgs: {
+  name = "hibernate";
+
+  nodes = {
+    machine = { config, lib, pkgs, ... }: with lib; {
+      virtualisation.emptyDiskImages = [ config.virtualisation.memorySize ];
+
+      systemd.services.backdoor.conflicts = [ "sleep.target" ];
+
+      swapDevices = mkOverride 0 [ { device = "/dev/vdb"; } ];
+
+      networking.firewall.allowedTCPPorts = [ 4444 ];
+
+      systemd.services.listener.serviceConfig.ExecStart = "${pkgs.netcat}/bin/nc -l -p 4444";
+    };
+
+    probe = { config, lib, pkgs, ...}: {
+      environment.systemPackages = [ pkgs.netcat ];
+    };
+  };
+
+  # 9P doesn't support reconnection to virtio transport after a hibernation.
+  # Therefore, machine just hangs on any Nix store access.
+  # To work around it we run a daemon which listens to a TCP connection and
+  # try to connect to it as a test.
+
+  testScript =
+    ''
+      $machine->waitForUnit("multi-user.target");
+      $machine->succeed("mkswap /dev/vdb");
+      $machine->succeed("swapon -a");
+      $machine->startJob("listener");
+      $machine->succeed("systemctl hibernate &");
+      $machine->waitForShutdown;
+      $machine->start;
+      $probe->waitForUnit("network.target");
+      $probe->waitUntilSucceeds("echo test | nc -c machine 4444");
+    '';
+
+})