}

    @Test
    public void test_toLineString() {
        assertEquals("aaa=>a", new StemmerOverrideItem(1, "aaa", "a").toLineString());
        assertEquals("=>", new StemmerOverrideItem(1, "", "").toLineString());
    }

        // When newInput is set back to null
        item.setNewInput(null);
        assertEquals("original", item.toLineString());
    }

    @Test
    public void test_toLineString_withEmptyInput() {
        // Test toLineString with empty original input
        StopwordsItem item = new StopwordsItem(1, "");
        assertEquals("", item.toLineString());

        item.setNewInput("new");

        assertEquals("a=>b", new SynonymItem(1, new String[] { "a" }, new String[] { "b" }).toLineString());
        assertEquals("A,a=>B,b", new SynonymItem(1, new String[] { "A", "a" }, new String[] { "B", "b" }).toLineString());
        assertEquals("A,a", new SynonymItem(1, new String[] { "A", "a" }, new String[] { "A", "a" }).toLineString());

    }

    /**
     * Converts the item to a string representation for writing to a file.
     *
     * @return A string in the format "input=>output".
     */
    public String toLineString() {
        if (isUpdated()) {
            return newInput + "=>" + newOutput;
        }
        return input + "=>" + output;
    }

     * If the item has pending updates, the new values are used; otherwise, the current values are used.
     *
     * @return compact string representation of the mapping rule
     */
    public String toLineString() {
        if (isUpdated()) {
            return StringUtils.join(newInputs, ",") + "=>" + newOutput;
        }
        return StringUtils.join(inputs, ",") + "=>" + output;
    }

        public KuromojiItem write(final KuromojiItem oldItem) {
            try {
                if (item == null || item.getId() != oldItem.getId() || !item.isUpdated()) {
                    writer.write(oldItem.toLineString());
                    writer.write(Constants.LINE_SEPARATOR);
                    return oldItem;
                }
                if (!item.equals(oldItem)) {

        assertEquals("new1,new2,new3=>newOutput", item.toLineString());
    }

    @Test
    public void test_toLineString_withSingleInput() {
        String[] inputs = { "single" };
        CharMappingItem item = new CharMappingItem(1L, inputs, "output");

        assertEquals("single=>output", item.toLineString());
    }

    @Test
    public void test_toLineString_withEmptyInputs() {

        public SynonymItem write(final SynonymItem oldItem) {
            try {
                if (item == null || item.getId() != oldItem.getId() || !item.isUpdated()) {
                    writer.write(oldItem.toLineString());
                    writer.write(Constants.LINE_SEPARATOR);
                    return oldItem;
                }
                if (!item.equals(oldItem)) {

        public CharMappingItem write(final CharMappingItem oldItem) {
            try {
                if (item == null || item.getId() != oldItem.getId() || !item.isUpdated()) {
                    writer.write(oldItem.toLineString());
                    writer.write(Constants.LINE_SEPARATOR);
                    return oldItem;
                }
                if (!item.equals(oldItem)) {

        // Debug: print what we actually got
        if (result.size() > 0) {
            for (CharMappingItem item : result) {
                System.out.println("Unexpected item: " + item.toLineString());
            }
        }

        // An empty file should return no items
        assertEquals("Empty file should have no items", 0, result.size());