Can i test stage buttons with TestFX and JUnit?

I am doing a test class thats verify some things in my window, and i want to know if i can test stage buttons(like know if the window is resizeable, what happend if i click in close request, ...).

Scene scene = new Scene(root);
        //Stage Properties
        stage.setScene(scene);
        stage.setTitle("LogIn");
        stage.setResizable(false);
        stage.setOnShowing(this::handleWindowShowing);
        stage.setOnCloseRequest(this::closeRequest);

I'm really lost in this because i don't know how can I test it, including respective Alerts for example when i click onCloseRequest, shows me a modal alert asking if is he sure with two buttons.

public void closeRequest(WindowEvent event) {
        Alert alert = new Alert(Alert.AlertType.CONFIRMATION);
        alert.setHeaderText("Close confirmation");
        alert.setTitle("Exit Window");
        alert.setContentText("Are you sure that want close the application?");
        alert.initOwner(stage);
        alert.initModality(Modality.WINDOW_MODAL);
        Optional<ButtonType> result = alert.showAndWait();
        if (result.get() == ButtonType.OK) {
            stage.close();
            Platform.exit();

        } else {
            event.consume();
        }
    }

Is this possible? How can i test it?
Thank you for your help.