add test

test/test.nix

@@ -0,0 +1,21 @@
+# ./tests/hello-world-server.nix
+(import ./lib.nix) {
+  name = "from-nixos";
+  nodes = {
+    # `self` here is set by using specialArgs in `lib.nix`
+    node1 = { self, pkgs, ... }: {
+      imports = [ self.nixosModules.zineshop ];
+
+      services.zineshop.enable = true;
+      environment.systemPackages = [ pkgs.curl ];
+    };
+  };
+
+  testScript = ''
+    start_all() # wait for our service to start
+    node1.wait_for_unit("zineshop.service")
+    output = node1.succeed("curl localhost:8080")
+    # Check if our webserver returns the expected result
+    assert "Zine Shop" in output, f"'{output}' does not contain 'Zine Shop'"
+  '';
+}