我正在尝试为JavaFX编写测试用例，如何开始？

Question

这是我的代码，我无法编写Junit测试用例。我是第一次编写测试用例，这是我第一次使用Javafx编写测试用例，而且我也不怎么开始用Javafx编写测试用例。我正在使用javafx8，并且正在使用此jar文件。

junit 4.12
hamcrest 1.3
mockito-all-1.9.5
testfx-core-4.0.14-alpha
TestNG 6.8.1-testing-6.8.1-dist.jar

public class SampleController implements Initializable {
    @FXML
    private Label label;
    @FXML
    private Button applyButton;
    @FXML
    private TextField firstName;
    @FXML
    private TextField lastName;

    /**
     * Initializes the controller class.
     */
    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
        applyButton.disableProperty().bind(
                firstName.textProperty().isEmpty()
                        .or(
                                lastName.textProperty().isEmpty()
                        ));
    }

    @FXML
    private void applyButtonClicked(ActionEvent event) {

        label.setText(firstName.getText());
    }

}


// this my respective test class

public class SampleControllerNGTest {

    public SampleControllerNGTest() {
    }

    @BeforeClass
    public static void setUpClass() throws Exception {
    }

    @AfterClass
    public static void tearDownClass() throws Exception {
    }

    @BeforeMethod
    public void setUpMethod() throws Exception {
    }

    @AfterMethod
    public void tearDownMethod() throws Exception {
    }

    /**
     * Test of initialize method, of class SampleController.
     */
    @Test
    public void testInitialize() {
        System.out.println("initialize");
        URL url = null;
        ResourceBundle rb = null;
        SampleController instance = new SampleController();
        instance.initialize(url, rb);
        // TODO review the generated test code and remove the default call to fail.
    fail("The test case is a prototype.");

    }

}