Basic JUnit test for JavaFX 8

Question

I want to create basic JUnit test for JavaFX 8 application. I have this simple code sample:

public class Main extends Application {
    public static void main(String[] args) {
        Application.launch(args);
    }
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Tabs");
        Group root = new Group();
        Scene scene = new Scene(root, 400, 250, Color.WHITE);
        TabPane tabPane = new TabPane();
        BorderPane borderPane = new BorderPane();
        for (int i = 0; i < 5; i++) {
            Tab tab = new Tab();
            tab.setText("Tab" + i);
            HBox hbox = new HBox();
            hbox.getChildren().add(new Label("Tab" + i));
            hbox.setAlignment(Pos.CENTER);
            tab.setContent(hbox);
            tabPane.getTabs().add(tab);
        }
        // bind to take available space
        borderPane.prefHeightProperty().bind(scene.heightProperty());
        borderPane.prefWidthProperty().bind(scene.widthProperty());

        borderPane.setCenter(tabPane);
        root.getChildren().add(borderPane);
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}

I only have this code so far:

import javafx.application.Application;
import javafx.stage.Stage;
import org.junit.BeforeClass;

public class BasicStart extends Application {

    @BeforeClass
    public static void initJFX() {
        Thread t = new Thread("JavaFX Init Thread") {
            @Override
            public void run() {
                Application.launch(BasicStart.class, new String[0]);
            }
        };
        t.setDaemon(true);
        t.start();
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        // noop
    }
}

Can you tell me how I can create JUnit test for the above code?

Answer 1

I use a Junit Rule to run unit tests on the JavaFX thread. The details are in this post. Just copy the class from that post and then add this field to your unit tests.

@Rule public JavaFXThreadingRule javafxRule = new JavaFXThreadingRule();

This code works for both JavaFX 2 and JavaFX 8.

Answer 2

The easiest aproach is the following:

import javafx.application.Platform;
import javafx.embed.swing.JFXPanel;
import javafx.stage.Stage;

import org.junit.Test;

public class BasicStart {

    @Test
    public void testA() throws InterruptedException {
        Thread thread = new Thread(new Runnable() {

            @Override
            public void run() {
                new JFXPanel(); // Initializes the JavaFx Platform
                Platform.runLater(new Runnable() {

                    @Override
                    public void run() {
                        new Main().start(new Stage()); // Create and
                                                        // initialize
                                                        // your app.

                    }
                });
            }
        });
        thread.start();// Initialize the thread
        Thread.sleep(10000); // Time to use the app, with out this, the thread
                                // will be killed before you can tell.
    }

}

Hope it helps!

Answer 3

Based on Brian Blonski 's answer I created a JUnit-Testrunner, that does essentially the same thing, but is a bit simpler to use in my opinion. Using it, your test would look like this:

@RunWith( JfxTestRunner.class )
public class MyUnitTest
{
  @Test
  public void testMyMethod()
  {
   //...
  }
}