anchor.diff:              bonusHistory: [],
             );
   
  -          final bonusLetter = _getBonusLetter(game);
  +          await game.ready();
  +          final bonusLetter = game.descendants().whereType<BonusLetter>().first;
  +          bonusLetter.activate();
   
             expect(
               bonusLetter.listenWhen(const GameState.initial(), state),
  
positive.code:       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,
  
negative.code:             bonusHistory: [],
            );
  
            await game.ready();
            final bonusLetter = game.descendants().whereType<BonusLetter>().first;
            bonusLetter.activate();
  
            bonusLetter.onNewState(state);
            await tester.pump();
  