nginx-sso: add passthru.tests

pkgs/servers/nginx-sso/default.nix

@@ -1,4 +1,4 @@
-{ buildGoPackage, fetchFromGitHub, stdenv }:
+{ buildGoPackage, fetchFromGitHub, stdenv, nixosTests }:
 
 buildGoPackage rec {
   pname = "nginx-sso";
@@ -19,6 +19,10 @@ buildGoPackage rec {
     cp -R $src/frontend $out/share
   '';
 
+  passthru.tests = {
+    inherit (nixosTests) nginx-sso;
+  };
+
   meta = with stdenv.lib; {
     description = "SSO authentication provider for the auth_request nginx module";
     homepage = "https://github.com/Luzifer/nginx-sso";