@Test
public void testReadListToString() {

        String expectedJsonString = "[\"hdfs\",\"hive\",\"knox\"]";
        List<String> testList = new ArrayList<String>();
        testList.add("hdfs");
        testList.add("hive");
        testList.add("knox");
        String actualJsonString = jsonUtil.readListToString(testList);
        Assert.assertEquals(expectedJsonString, actualJsonString);
}