### Question:
JSONUtil { public String readMapToString(Map<?, ?> map) { ObjectMapper mapper = new ObjectMapper(); String jsonString = null; try { jsonString = mapper.writeValueAsString(map); } catch (JsonParseException e) { throw restErrorUtil.createRESTException( "Invalid input data: " + e.getMessage(), MessageEnums.INVALID_INPUT_DATA); } catch (JsonMappingException e) { throw restErrorUtil.createRESTException( "Invalid input data: " + e.getMessage(), MessageEnums.INVALID_INPUT_DATA); } catch (IOException e) { throw restErrorUtil.createRESTException( "Invalid input data: " + e.getMessage(), MessageEnums.INVALID_INPUT_DATA); } return jsonString; }  File writeJsonToFile(ViewBaseBean viewBean, String fileName); Map<String, String> jsonToMap(String jsonStr); String readMapToString(Map<?, ?> map); String readListToString(List<?> list); String writeObjectAsString(ViewBaseBean vObj);  }### Answer:
@Test public void testReadMapToString() { Map<?, ?> map = new HashMap<Object, Object>(); String value = jsonUtil.readMapToString(map); Assert.assertNotNull(value); }