@SneakyThrows
    public static String toString(InputStream input, String encoding) {
        if (input == null) {
            return StringUtil.EMPTY;
        }
        return (null == encoding) ? toString(new InputStreamReader(input, Constants.ENCODE))
                : toString(new InputStreamReader(input, encoding));
    }
@Test
    public void testToStringReader() throws IOException {
        String testString = "test string";
        Reader reader = new StringReader(testString);
        String result = IoUtil.toString(reader);
        Assert.assertEquals(testString, result);
    }