anchor.diff:        tester.widgetTest(
           'only listens when there is a change on the letter status',
           (game, tester) async {
  -          await game.ready();
  -
             const state = GameState(
               score: 0,
               balls: 2,
  
positive.code:             bonusHistory: [],
            );
  
            final bonusLetter = _getBonusLetter(game);
  
            expect(
              bonusLetter.listenWhen(const GameState.initial(), state),
  
negative.code:             bonusHistory: [],
            );
  
            await game.ready();
            final bonusLetter = game.descendants().whereType<BonusLetter>().first;
            bonusLetter.activate();
  
            bonusLetter.onNewState(state);
            await tester.pump();
  