public void test_CACHE_KEY_SPLITTER() {
        assertEquals('\n', PopularWordHelper.CACHE_KEY_SPLITTER);
    }

    @Test
    public void test_getCacheKey_longStrings() {
        String seed = "very_long_seed_" + "x".repeat(100);
        String[] tags = { "long_tag_" + "y".repeat(50), "another_long_tag_" + "z".repeat(50) };
        String[] roles = { "long_role_" + "a".repeat(50) };