checks: Add assertion that the module defaults work

nix/checks/open-homepage.nix

@@ -4,32 +4,38 @@
 }:
 nixosTest {
   nodes = {
+    # Host with just the default configuration
+    defaults = {
+      imports = [self.nixosModules.default];
+      services.tlaternet-webserver.enable = true;
+    };
+
     host = {
-      config,
-      lib,
-      pkgs,
-      ...
-    }: {
       imports = [self.nixosModules.default];
 
       services.tlaternet-webserver = {
         enable = true;
         listen = {
           addr = "0.0.0.0";
-          port = 8000;
+          port = 8080;
         };
       };
 
-      networking.firewall.allowedTCPPorts = [8000];
+      networking.firewall.allowedTCPPorts = [8080];
     };
 
-    client = {pkgs, ...}: {};
+    client = {};
   };
 
   testScript = ''
     start_all()
 
-    host.wait_for_unit("default.target")
-    client.succeed("curl --fail http://host:8000/ >&2")
+    # Assert that the defaults work
+    defaults.wait_for_unit("tlaternet-webserver.service")
+    defaults.succeed("curl --fail http://localhost:8000 >&2")
+
+    # Assert that we can listen on a public interface
+    host.wait_for_unit("tlaternet-webserver.service")
+    client.succeed("curl --fail http://host:8080 >&2")
   '';
 }