How can I use two test methods in single Test Class for JavaFx UI testing?

Question

I am currently facing an exception while loading the UI controller.

Have written two separate methods for testing client requests for a server while loading files.

I have start methods which loads UI controller-

@Override
public void start(Stage stage) throws IOException {

and test methods are as follows:

1. First test

   @Test
   @DisplayName("load the files")
   public void testRoutineA() throws URISyntaxException, NullPointerException, IOException {
   

2. Second test

   @Test
   public static void testRoutineB() throws IOException {
   

Issue:

• testRoutineA runs fine and load the UI.
• But when testRoutineB runs it again call the Sart method and throws exception:

Exception in Async Thread --- Failed to load FXML files.

Any suggestion how to use both methods ?