Checks: add nixosIntegration test example to hello-service

clanServices/hello-world/tests/vm/default.nix

@@ -0,0 +1,42 @@
+{
+  pkgs,
+  self,
+  clanLib,
+  module,
+  ...
+}:
+clanLib.test.makeTestClan {
+  inherit pkgs self;
+  nixosTest = (
+    { ... }:
+    {
+      name = "service-hello-test";
+
+      clan = {
+        directory = ./.;
+        inventory = {
+          machines.peer1 = { };
+
+          instances."test" = {
+            module.name = "hello-service";
+            roles.peer.machines.peer1 = { };
+          };
+
+          modules = {
+            hello-service = module;
+          };
+        };
+      };
+
+      testScript =
+        { nodes, ... }:
+        ''
+          start_all()
+
+          # peer1 should have the 'hello' file
+          value = peer1.succeed("cat ${nodes.peer1.clan.core.vars.generators.hello.files.hello.path}")
+          assert value.strip() == "Hello world from peer1", value
+        '';
+    }
+  );
+}

clanServices/hello-world/tests/vm/sops/users/admin/key.json

@@ -0,0 +1,4 @@
+{
+  "publickey": "age1qm0p4vf9jvcnn43s6l4prk8zn6cx0ep9gzvevxecv729xz540v8qa742eg",
+  "type": "age"
+}

clanServices/hello-world/tests/vm/vars/per-machine/peer1/hello/hello/value

@@ -0,0 +1 @@
+Hello world from peer1