assertEquals("日本語,中文,한국어", result);
    }

    @ParameterizedTest
    @DisplayName("Should handle various delimiter types")
    @MethodSource("provideDelimiters")
    void testJoinWithVariousDelimiters(String delimiter, String expected) {
        String result = StringUtil.join(delimiter, "A", "B", "C");
        assertEquals(expected, result);
    }

    private static Stream<Arguments> provideDelimiters() {