unmount method
void
unmount()
Implementation
void unmount() {
if (_rootElement != null) {
_unmountElement(_rootElement!);
_rootElement = null;
}
FocusManager.instance.dispose();
keyboard.dispose();
_testInstance = null;
WidgetsBinding.resetInstance();
RendererBinding.resetInstance();
ServicesBinding.resetInstance();
SchedulerBinding.resetInstance();
}