nixos/activation-script: Add a test

nixos/tests/all-tests.nix

@@ -406,6 +406,7 @@ in
   unit-php = handleTest ./web-servers/unit-php.nix {};
   upnp = handleTest ./upnp.nix {};
   usbguard = handleTest ./usbguard.nix {};
+  user-activation-scripts = handleTest ./user-activation-scripts.nix {};
   uwsgi = handleTest ./uwsgi.nix {};
   v2ray = handleTest ./v2ray.nix {};
   vault = handleTest ./vault.nix {};

nixos/tests/user-activation-scripts.nix

@@ -0,0 +1,33 @@
+import ./make-test-python.nix ({ lib, ... }: {
+  name = "user-activation-scripts";
+  meta = with lib.maintainers; { maintainers = [ chkno ]; };
+
+  machine = {
+    system.userActivationScripts.foo = "mktemp ~/user-activation-ran.XXXXXX";
+    users.users.alice = {
+      initialPassword = "pass1";
+      isNormalUser = true;
+    };
+  };
+
+  testScript = ''
+    def verify_user_activation_run_count(n):
+        machine.succeed(
+            '[[ "$(find /home/alice/ -name user-activation-ran.\\* | wc -l)" == %s ]]' % n
+        )
+
+
+    machine.wait_for_unit("multi-user.target")
+    machine.wait_for_unit("getty@tty1.service")
+    machine.wait_until_tty_matches(1, "login: ")
+    machine.send_chars("alice\n")
+    machine.wait_until_tty_matches(1, "Password: ")
+    machine.send_chars("pass1\n")
+    machine.send_chars("touch login-ok\n")
+    machine.wait_for_file("/home/alice/login-ok")
+    verify_user_activation_run_count(0)  # Wrong!  Should be 1
+
+    machine.succeed("/run/current-system/bin/switch-to-configuration test")
+    verify_user_activation_run_count(1)  # Wrong!  Should be 2
+  '';
+})