MainPaneControllerTest.java

package fx.fxml.view.fxml;

import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import org.junit.Test;
import org.loadui.testfx.GuiTest;
import org.mockito.Mockito;

import java.io.IOException;

public class MainPaneControllerTest extends GuiTest {
    private MainPaneController controller;

    @Override
    protected Parent getRootNode() {
        FXMLLoader loader = new FXMLLoader();
        loader.setLocation(MainPaneController.class.getResource("MainPane.fxml"));
        loader.setControllerFactory(type -> Mockito.spy(new MainPaneController()));

        try {
            Parent root = loader.load();
            controller = loader.getController();
            return root;

        }
        catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Test
    public void selectedLeftItemIsBound() {
        controller.getLeftListView().getItems().add("test item");
        click("test item");
    }
}