To be implemented to provide a test case that is then executed by ComposeTestRule or can be used in benchmarks.
This method is guaranteed to be called only once per class lifetime.
@Composable abstract fun emitContent(): Unit
This method is guaranteed to be called only once per class lifetime. In case a benchmark needs to measure initial composition / measure / layout / draw it re-creates this class every time it needs to call emitContent again. This ensures that any setup you do in this class is not shared between multiple calls of this method. So the init method is a good place to setup / clean your caches.