How do I make unit tests for a LibGDX application that uses SpriteBatch and other OpenGL methods/classes?

Question

I have been attempting to use the headless-backend library to help create unit tests for my own subclass (MainMenuScreen) of the ScreenAdapter class, but A) MainMenuScreen uses the SpriteBatch class in its initialization, and as far as I know there isn't a way to mock that, and B) I'm not entirely sure if I'm setting up the headless application correctly. I am using Maven for dependencies, JUnit for testing, and JaCoco for test coverage info.

My question(s): how do I set up a headless application for MainMenuClass? If that can't be done, is there some other way to unit test classes that use LibGDX and OpenGL methods/classes (especially SpriteBatch)?

What I have already researched:

• https://javadoc.io/doc/com.badlogicgames.gdx/gdx-backend-headless/latest/index.html: gdx-backend JavaDocumentation; very sparse, with no examples or explanations of how the code works.
• Is there any way to create integration test for libGDX application?: the answer right below the question has the best example I can find of how to use HeadlessApplication in the setup method. However, I think it requires me to have created a headless version of the class I want to test; I don't know how to do that.
• https://github.com/TomGrill/gdx-testing/tree/master: Tom Grill's gdx-testing library. I'm 99% sure all this does is take LibGDX dependent code and turn it into a headless application, but every attempt I have made to use it has failed miserably.

My unit test code:

public class MainMenuTest {
    final MazeGame testGame = mock(MazeGame.class);
    private MainMenuScreen testScreen;
    private HeadlessApplication app;


    // TODO: get the headless backend working; the current problem is getting OpenGL methods working
    u/BeforeEach
    public void setup() {
        MockGraphics mockGraphics = new MockGraphics();
        Gdx.graphics = mockGraphics;
        Gdx.gl = mock(GL20.class);

        testScreen = new MainMenuScreen(testGame);
        HeadlessApplicationConfiguration config = new HeadlessApplicationConfiguration();
        app = new HeadlessApplication(new ApplicationListener() {
            u/Override
            public void create() {
                // Set the screen to MainMenuScreen directly
                testScreen = new MainMenuScreen(testGame); // Pass null or a mock game instance if necessary
            }
            u/Override
            public void resize(int width, int height) {}
            u/Override
            public void render() {
                testScreen.render(1 / 60f); // Simulate a frame render
            }
            u/Override
            public void pause() {}
            u/Override
            public void resume() {}
            u/Override
            public void dispose() {
                testScreen.dispose();
            }
        }, config);
    }


    /**
     * Test to see if the start button works.
     */
    u/Test
    public void startButtonWorks() {
        // doesn't click start button
        Button startButton = testScreen.getStartButton();
        assertEquals(false, startButton.isChecked());


        // clicks start button
        ((ChangeListener) (startButton.getListeners().first())).changed(new ChangeEvent(), startButton);
        assertEquals(true, startButton.isChecked());
    }
}

Current error during mvn test: enter image description here

Thanks in advance, and let me know if this isn't the right place to post this/I need to provide more info.