Test: Added coverage for 4 lines because I want the 80%

Author: UO283615

api/src/test/java/lab/en2b/quizapi/game/GameServiceTest.java

@@ -476,4 +476,24 @@ public void testGetGameModes(){
         assertFalse(gameService.getQuestionGameModes().isEmpty());
     }
 
+    @Test
+    public void testGameSetQuestionCategoriesInvalidGameMode(){
+        Game g = new Game();
+        g.setGameMode(GameMode.KIWI_QUEST);
+        assertThrows(IllegalStateException.class, () -> g.setQuestionCategoriesForCustom(List.of(QuestionCategory.GEOGRAPHY)));
+    }
+    @Test
+    public void testGameSetQuestionCategoriesInvalidNullCategories(){
+        Game g = new Game();
+        g.setGameMode(GameMode.CUSTOM);
+        assertThrows(IllegalArgumentException.class, () -> g.setQuestionCategoriesForCustom(null));
+    }
+    @Test
+    public void testGameSetQuestionCategoriesInvalidEmptyCategories(){
+        Game g = new Game();
+        g.setGameMode(null);
+        g.setGameMode(GameMode.CUSTOM);
+        List<QuestionCategory> qc = new ArrayList<>();
+        assertThrows(IllegalArgumentException.class, () -> g.setQuestionCategoriesForCustom(qc));
+    }
 }