nixosTests.homepage-dashboard: add test for ping property on service

Use homepage's API to ensure that ping works

nixos/tests/homepage-dashboard.nix

@@ -21,10 +21,23 @@
           ];
         }
       ];
+      services = [
+        {
+          Machines = [
+            {
+              Localhost = {
+                ping = "127.0.0.1";
+              };
+            }
+          ];
+        }
+      ];
     };
   };
 
   testScript = ''
+    import json
+
     # Ensure the services are started on managed machine
     machine.wait_for_unit("homepage-dashboard.service")
     machine.wait_for_open_port(8082)
@@ -40,5 +53,9 @@
     # Ensure that we see the custom bookmarks on the page
     page = machine.succeed("curl --fail http://127.0.0.1:8082/api/bookmarks")
     assert "nixpkgs" in page, "Custom bookmarks not found"
+
+    # Ensure that the ping command works
+    response = machine.succeed("curl --fail \"http://localhost:8082/api/ping?groupName=Machines&serviceName=Localhost\"")
+    assert json.loads(response)["alive"] is True, "Ping to localhost failed"
   '';
 }