Run your app in headless mode for testing

This can be useful for running app simulations during integration tests without spawning a window which can be problematic in a testing environment.

struct HeadlessRenderPlugin;

impl Plugin for HeadlessRenderPlugin {
    fn build(&self, app: &mut App) {
        app.add_plugin(WindowPlugin::default())
            .add_plugin(AssetPlugin::default())
            .add_plugin(ScenePlugin::default())
            .add_plugin(RenderPlugin {
                wgpu_settings: WgpuSettings {
                    backends: None,
                    ..Default::default()
                },
            })
            .add_plugin(ImagePlugin::default());
    }
}