CharMappingItem item = new CharMappingItem(1L, inputs, "oldOutput");

        item.setNewInputs(new String[] { "new1", "new2", "new3" });
        item.setNewOutput("newOutput");

        // Should use new values when updated
        assertEquals("new1,new2,new3=>newOutput", item.toLineString());
    }

    @Test
    public void test_toLineString_withSingleInput() {
        String[] inputs = { "single" };

        }
    }

    // Test update with InputStream
    @Test
    public void test_update_withInputStream() throws IOException {
        String content = "new1\n" + "new2\n" + "new3\n";

        InputStream is = new ByteArrayInputStream(content.getBytes(StandardCharsets.UTF_8));
        stopwordsFile.update(is);

        assertEquals(3, stopwordsFile.stopwordsItemList.size());