public void test_execute_emptyList() {
        String result = scoreUpdater.execute();
        assertEquals("", result);
    }

    // Test execute with single booster
    @Test
    public void test_execute_singleBooster() {
        TestScoreBooster booster = new TestScoreBooster(100L);
        scoreUpdater.addScoreBooster(booster);

        String result = scoreUpdater.execute();