message: Fix DER vs PEM confusion in node_frontend_test
diff: @@ -211,13 +211,14 @@ TEST_CASE("Add a node to an opening service")
  crypto::KeyPairPtr kp = crypto::make_key_pair();
  auto v = crypto::make_verifier(
  kp->self_sign("CN=Other Joiner", valid_from, valid_to));
  - const auto caller = v->cert_der();
  + const auto new_caller = v->cert_pem();
  // Network node info is empty (same as before)
  JoinNetworkNodeToNode::In join_input;
  join_input.public_encryption_key = node_public_encryption_key;
  - auto http_response = frontend_process(frontend, join_input, "join", caller);
  + auto http_response =
  + frontend_process(frontend, join_input, "join", new_caller);
  check_error(http_response, HTTP_STATUS_BAD_REQUEST);
  check_error_message(http_response, "A node with the same node address");
  @@ -290,12 +291,13 @@ TEST_CASE("Add a node to an open service")
  crypto::KeyPairPtr kp = crypto::make_key_pair();
  auto v =
  crypto::make_verifier(kp->self_sign("CN=Joiner", valid_from, valid_to));
  - const auto caller = v->cert_der();
  + const auto new_caller = v->cert_pem();
  // Network node info is empty (same as before)
  JoinNetworkNodeToNode::In join_input;
  - auto http_response = frontend_process(frontend, join_input, "join", caller);
  + auto http_response =
  + frontend_process(frontend, join_input, "join", new_caller);
  check_error(http_response, HTTP_STATUS_BAD_REQUEST);
  check_error_message(http_response, "A node with the same node address");
  