Is there any way to create integration test for libGDX application?

Question

I apologize if the question is duplicated, but I can't find any information about this.

I know that I can use JUnit to create simple unit tests, but I can't run it on android/iOS devices. If I understand correctly, I can use Instrumented Unit Tests, but they are for android platform only. In this case, I can't test functions from libGDX core (am I wrong?). So, I'm interested, how can I run my tests on devices?

Answer 1

Testing libGDX applications is not an easy topic but with a good architecture it is possible. The crucial point is to separate the rendering part from the business logic you want to test. Rendering always requires an OpenGL context and will just break if you try to run it without that. You can actually write tests that require OpenGL if you don't plan to run them on a headless build server but just on your desktop.

That being said, testing of libGDX apps is mostly centered around the usage of HeadlessApplication that makes your libGDX-dependent code runnable in your test environment. If you want to start he whole game in a test, you need a headless version of it (here "MyGameHeadlessApplication"). Then you can initialize it like this:

    private MyGameHeadlessApplication application;

    @Before
    public void setUp() throws Exception {
        HeadlessApplicationConfiguration config = new HeadlessApplicationConfiguration();
        config.renderInterval = 1F / 30F;
        application = new MyGameHeadlessApplication();
        new HeadlessApplication(this.application , config);
    }

For testing smaller parts that depend on libGDX, there is a very conventient library available: The gdx-testing project contains a GdxTestRunner that wraps your tests in a HeadlessApplication and allows you something like this (from the gdx-testing example):

@RunWith(GdxTestRunner.class)
public class MySuperTestClass {
    @Test
    public void bestTestInHistory() {
        // libgdx dependent code runs here
    }
}

On top of that I had a little problem with my assets folder that couldn't be found in the tests in the first place. I fixed that by setting workingDir for tests in my build.gradle. And of cours make sure to have all the needed dependencies (also e.g. box2d if you need that in your tests). In my setup I have all tests in the "core" project:

project(":core") {
    apply plugin: "java"

    test {
        project.ext.assetsDir = new File("./assets")
        workingDir = project.ext.assetsDir
    }

    dependencies {
        testCompile "com.badlogicgames.gdx:gdx-backend-headless:$gdxVersion"
        testCompile "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-desktop"
        testCompile "com.badlogicgames.gdx:gdx-box2d-platform:$gdxVersion:natives-desktop"
        // ... more dependencies here ...

See also Unit-testing of libgdx-using classes