nixos/libinput: add module tests

nixos/tests/all-tests.nix

@@ -228,9 +228,10 @@ in
   kubernetes = handleTestOn ["x86_64-linux"] ./kubernetes {};
   latestKernel.login = handleTest ./login.nix { latestKernel = true; };
   leaps = handleTest ./leaps.nix {};
+  libinput = handleTest ./libinput.nix {};
   libreddit = handleTest ./libreddit.nix {};
-  lidarr = handleTest ./lidarr.nix {};
   libreswan = handleTest ./libreswan.nix {};
+  lidarr = handleTest ./lidarr.nix {};
   lightdm = handleTest ./lightdm.nix {};
   limesurvey = handleTest ./limesurvey.nix {};
   litestream = handleTest ./litestream.nix {};

nixos/tests/libinput.nix

@@ -0,0 +1,38 @@
+import ./make-test-python.nix ({ ... }:
+
+{
+  name = "libinput";
+
+  machine = { ... }:
+    {
+      imports = [
+        ./common/x11.nix
+        ./common/user-account.nix
+      ];
+
+      test-support.displayManager.auto.user = "alice";
+
+      services.xserver.libinput = {
+        enable = true;
+        mouse = {
+          naturalScrolling = true;
+          leftHanded = true;
+          middleEmulation = false;
+          horizontalScrolling = false;
+        };
+      };
+    };
+
+  testScript = ''
+    def expect_xserver_option(option, value):
+        machine.succeed(f"""cat /var/log/X.0.log | grep -F 'Option "{option}" "{value}"'""")
+
+    machine.start()
+    machine.wait_for_x()
+    machine.succeed("""cat /var/log/X.0.log | grep -F "Using input driver 'libinput'" """)
+    expect_xserver_option("NaturalScrolling", "on")
+    expect_xserver_option("LeftHanded", "on")
+    expect_xserver_option("MiddleEmulation", "off")
+    expect_xserver_option("HorizontalScrolling", "off")
+  '';
+})

pkgs/development/libraries/libinput/default.nix

@@ -3,6 +3,7 @@
 , documentationSupport ? false, doxygen, graphviz # Documentation
 , eventGUISupport ? false, cairo, glib, gtk3 # GUI event viewer support
 , testsSupport ? false, check, valgrind, python3
+, nixosTests
 }:
 
 let
@@ -76,6 +77,10 @@ stdenv.mkDerivation rec {
 
   doCheck = testsSupport && stdenv.hostPlatform == stdenv.buildPlatform;
 
+  passthru.tests = {
+    libinput-module = nixosTests.libinput;
+  };
+
   meta = with lib; {
     description = "Handles input devices in Wayland compositors and provides a generic X.Org input driver";
     homepage    = "https://www.freedesktop.org/wiki/Software/libinput/";