inventory tests: add vars support

- Add support for leading vars
- Extend test to test for vars support
- Improve update-vars.py to take test name as argument

checks/lib/test-inventory.nix

@@ -47,6 +47,20 @@ in
           documentation.enable = lib.mkDefault false;
           nix.settings.min-free = 0;
           system.stateVersion = config.system.nixos.release;
+          boot.initrd.systemd.enable = false;
+
+          # setup for sops
+          sops.age.keyFile = "/run/age-key.txt";
+          system.activationScripts =
+            {
+              setupSecrets.deps = [ "age-key" ];
+              age-key.text = ''
+                echo AGE-SECRET-KEY-1PL0M9CWRCG3PZ9DXRTTLMCVD57U6JDFE8K7DNVQ35F4JENZ6G3MQ0RQLRV > /run/age-key.txt
+              '';
+            }
+            // lib.optionalAttrs (lib.filterAttrs (_: v: v.neededForUsers) config.sops.secrets != { }) {
+              setupSecretsForUsers.deps = [ "age-key" ];
+            };
         }
       );