nixos/irqbalance: add nixos test

nixos/tests/all-tests.nix

@@ -765,6 +765,7 @@ in
   invoiceplane = runTest ./invoiceplane.nix;
   iodine = runTest ./iodine.nix;
   ipv6 = runTest ./ipv6.nix;
+  irqbalance = runTest ./irqbalance.nix;
   iscsi-multipath-root = runTest ./iscsi-multipath-root.nix;
   iscsi-root = runTest ./iscsi-root.nix;
   isso = runTest ./isso.nix;

nixos/tests/irqbalance.nix

@@ -0,0 +1,29 @@
+{ pkgs, lib, ... }:
+{
+  name = "irqbalance";
+  meta.maintainers = with lib.maintainers; [ h7x4 ];
+
+  nodes.machine =
+    { config, ... }:
+    {
+      virtualisation.cores = 2;
+      services.irqbalance.enable = true;
+
+      systemd.services.irqbalance.serviceConfig.ExecStart = [
+        ""
+        "${lib.getExe config.services.irqbalance.package} --journal --debug"
+      ];
+    };
+
+  testScript = ''
+    machine.wait_for_unit("irqbalance.service")
+
+    machine.wait_until_succeeds("journalctl -u irqbalance.service --grep='Package 0'")
+
+    unmanaged_irq_count = machine.succeed("journalctl -u irqbalance.service -o cat --grep 'affinity is now unmanaged' | sort -u | wc -l")
+
+    # The number of unmanaged IRQs is not entirely stable, but there is likely something
+    # wrong if any more that 2 queues are unmanaged
+    assert int(unmanaged_irq_count) <= 2
+  '';
+}

pkgs/by-name/ir/irqbalance/package.nix

@@ -9,6 +9,7 @@
   libcap_ng,
   enableSystemd ? lib.meta.availableOn stdenv.hostPlatform systemdMinimal,
   systemdMinimal,
+  nixosTests,
 }:
 
 stdenv.mkDerivation rec {
@@ -48,6 +49,8 @@ stdenv.mkDerivation rec {
       --replace-fail ' $IRQBALANCE_ARGS' ""
   '';
 
+  passthru.tests.nixos = nixosTests.irqbalance;
+
   meta = {
     homepage = "https://github.com/Irqbalance/irqbalance";
     changelog = lib.strings.optionalString (