refactor mutibility

tests/in_memory_test.rs

@@ -8,13 +8,14 @@ async fn opaque_key_registration_and_login_roundtrip() {
     let mut rng = OsRng;
     let server_setup = NKodeServerSetup::new(&mut rng);
     let server = InMemoryKeyServer::new(server_setup);
-    let auth_reg = OpaqueAuthRegister::new(server.clone());
+    let auth_reg = OpaqueAuthRegister::new(server);
     let auth_data = AuthenticationData::from_secret_key("a@b.com", b"supersecret16bytes");
     auth_reg.register(&auth_data).await.expect("registration should succeed");
     let login_reg = OpaqueAuthLogin::new(server);
     let _ =login_reg.login(&auth_data)
         .await
         .expect("login should succeed");
+    // assert!(!session_key.is_empty());
 }
 
 #[tokio::test]