refactor: multiplier max value 6 at game bloc

lib/game/bloc/game_bloc.dart

@@ -1,5 +1,5 @@
 // ignore_for_file: public_member_api_docs
-
+import 'dart:math' as math;
 import 'package:bloc/bloc.dart';
 import 'package:equatable/equatable.dart';
 import 'package:meta/meta.dart';
@@ -49,7 +49,11 @@ class GameBloc extends Bloc<GameEvent, GameState> {
 
   void _onIncreasedMultiplier(MultiplierIncreased event, Emitter emit) {
     if (!state.isGameOver) {
-      emit(state.copyWith(multiplier: state.multiplier + 1));
+      emit(
+        state.copyWith(
+          multiplier: math.min(state.multiplier + 1, 6),
+        ),
+      );
     }
   }
 

lib/game/bloc/game_event.dart

@@ -59,8 +59,6 @@ class SparkyTurboChargeActivated extends GameEvent {
 class MultiplierIncreased extends GameEvent {
   /// {@macro multiplier_increased_game_event}
   const MultiplierIncreased();
-  // TODO(ruimiguel): confirm that x6 is going to be the max value, to add
-  // assertion here
 
   @override
   List<Object?> get props => [];

test/game/bloc/game_bloc_test.dart

@@ -160,6 +160,31 @@ void main() {
         ],
       );
 
+      blocTest<GameBloc, GameState>(
+        "doesn't increase multiplier "
+        'when multiplier is 6 and game is not over',
+        build: GameBloc.new,
+        seed: () => const GameState(
+          score: 0,
+          multiplier: 5,
+          balls: 3,
+          rounds: 3,
+          bonusHistory: [],
+        ),
+        act: (bloc) => bloc
+          ..add(const MultiplierIncreased())
+          ..add(const MultiplierIncreased()),
+        expect: () => [
+          const GameState(
+            score: 0,
+            multiplier: 6,
+            balls: 3,
+            rounds: 3,
+            bonusHistory: [],
+          ),
+        ],
+      );
+
       blocTest<GameBloc, GameState>(
         "doesn't increase multiplier "
         'when game is over',