nixos/zram-generator: add test

nixos/tests/all-tests.nix

@@ -752,6 +752,7 @@ in {
   zigbee2mqtt = handleTest ./zigbee2mqtt.nix {};
   zoneminder = handleTest ./zoneminder.nix {};
   zookeeper = handleTest ./zookeeper.nix {};
+  zram-generator = handleTest ./zram-generator.nix {};
   zrepl = handleTest ./zrepl.nix {};
   zsh-history = handleTest ./zsh-history.nix {};
 }

nixos/tests/zram-generator.nix

@@ -0,0 +1,18 @@
+import ./make-test-python.nix {
+  name = "zram-generator";
+
+  nodes.machine = { pkgs, ... }: {
+    environment.etc."systemd/zram-generator.conf".text = ''
+      [zram0]
+      zram-size = ram / 2
+    '';
+    systemd.packages = [ pkgs.zram-generator ];
+    systemd.services."systemd-zram-setup@".path = [ pkgs.util-linux ]; # for mkswap
+  };
+
+  testScript = ''
+    machine.wait_for_unit("systemd-zram-setup@zram0.service")
+    assert "zram0" in machine.succeed("zramctl -n")
+    assert "zram0" in machine.succeed("swapon --show --noheadings")
+  '';
+}

pkgs/tools/system/zram-generator/default.nix

@@ -6,6 +6,7 @@
 , ronn
 , systemd
 , kmod
+, nixosTests
 }:
 
 stdenv.mkDerivation rec {
@@ -50,6 +51,10 @@ stdenv.mkDerivation rec {
     "SYSTEMD_SYSTEM_GENERATOR_DIR=$(out)/lib/systemd/system-generators"
   ];
 
+  passthru.tests = {
+    inherit (nixosTests) zram-generator;
+  };
+
   meta = with lib; {
     homepage = "https://github.com/systemd/zram-generator";
     license = licenses.mit;