refactor: used `descendants` to retrieve tested subject (#94)

* refactor: used descendants to retrieve the subject

* fix: included game.ready in tests

test/game/components/bonus_word_test.dart

@@ -196,15 +196,6 @@ void main() {
       final gameBloc = MockGameBloc();
       final tester = flameBlocTester(gameBloc: () => gameBloc);
 
-      BonusLetter _getBonusLetter(PinballGame game) {
-        return game.children
-            .whereType<BonusWord>()
-            .first
-            .children
-            .whereType<BonusLetter>()
-            .first;
-      }
-
       setUp(() {
         whenListen(
           gameBloc,
@@ -217,11 +208,11 @@ void main() {
         'adds BonusLetterActivated to GameBloc when not activated',
         (game, tester) async {
           await game.ready();
-
+          final bonusLetter = game.descendants().whereType<BonusLetter>().first;
-          _getBonusLetter(game).activate();
+          bonusLetter.activate();
+          await game.ready();
 
           await tester.pump();
-
           verify(() => gameBloc.add(const BonusLetterActivated(0))).called(1);
         },
       );
@@ -241,10 +232,11 @@ void main() {
             Stream.value(state),
             initialState: state,
           );
-          await game.ready();
 
-          _getBonusLetter(game).activate();
+          await game.ready();
-          await game.ready(); // Making sure that all additions are done
+          final bonusLetter = game.descendants().whereType<BonusLetter>().first;
+          bonusLetter.activate();
+          await game.ready();
 
           verifyNever(() => gameBloc.add(const BonusLetterActivated(0)));
         },
@@ -253,8 +245,6 @@ void main() {
       tester.widgetTest(
         'adds a ColorEffect',
         (game, tester) async {
-          await game.ready();
-
           const state = GameState(
             score: 0,
             balls: 2,
@@ -263,7 +253,9 @@ void main() {
             bonusHistory: [],
           );
 
-          final bonusLetter = _getBonusLetter(game);
+          await game.ready();
+          final bonusLetter = game.descendants().whereType<BonusLetter>().first;
+          bonusLetter.activate();
 
           bonusLetter.onNewState(state);
           await tester.pump();
@@ -278,8 +270,6 @@ void main() {
       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,
@@ -288,7 +278,9 @@ void main() {
             bonusHistory: [],
           );
 
-          final bonusLetter = _getBonusLetter(game);
+          await game.ready();
+          final bonusLetter = game.descendants().whereType<BonusLetter>().first;
+          bonusLetter.activate();
 
           expect(
             bonusLetter.listenWhen(const GameState.initial(), state),