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.
Inherited extension functions
This global operator is TEMPORARY, and should be removed whenever an answer for contextual composers is reached.
@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.