### Question:
CommonUtils { public static Date dateFormat(final String dateInString, String formatFrom, String formatTo) throws java.text.ParseException { String dateDormatter = "MM/dd/yyyy"; if (StringUtils.isNullOrEmpty(formatFrom)) { formatFrom = dateDormatter; } if (StringUtils.isNullOrEmpty(formatTo)) { formatTo = dateDormatter; } DateFormat dateFromFormater = new SimpleDateFormat(formatFrom); DateFormat dateToFormater = new SimpleDateFormat(formatTo); return dateToFormater.parse(dateToFormater.format(dateFromFormater.parse(dateInString))); }  static Boolean isEnvVariableExists(String envVariableName); static String getEnvVariableValue(String envVariableName); static String doHttpPost(final String url,  String requestBody); static String doHttpPut(final String url, final String requestBody); static boolean isValidResource(String esUrl); static Object buildQueryForExistingIssues(Map<String, Object> filter); static String getIndexNameFromRuleParam(Map<String, String> ruleParam); @SuppressWarnings("unchecked") static Map<String, String> flatNestedMap(String notation, Map<String, Object> nestedMap); static String getUniqueAnnotationId(Annotation annotation); static String getUniqueAnnotationId(String parentId, String ruleId); static String getUniqueIdForString(String inStr); static String hash(String s); static Map<String, String> createParamMap(String ruleParams); static String decrypt(String encryptedText); static Map<String, String> buildMapFromString(String input, String splitOn, String keyValueSeparator); static Long getElapseTimeSince(long startTime); static String getCurrentDateStringWithFormat(String timeZone, String format); static Date getDateFromString(final String dateInString, final String format); static Date dateFormat(final String dateInString, String formatFrom, String formatTo); static int compareDate(final Date firstDate, final Date lastDate); static boolean resourceCreatedBeforeCutoffData(final Date resourceCreationDate); static String doHttpPost(final String url, final String requestBody, final Map<String, String> headers); static String doHttpGet(final String url); static SSLContext createNoSSLContext(); static String getJsonString(final Object annotation); static String encryptB64(String plainText); static String decryptB64(String text); static String encrypt(String plainText, final String key); static String decrypt(String encryptedText, final String key); static String getPropValue(final String keyname); static String getTemplateContent(final String templateName); static String serializeToString(Object object); static Object deSerializeToObject(String jsonString); static Boolean doesAllHaveValue(String...strings );  }### Answer:
@Test public void dateFormat() throws Exception { Date response = CommonUtils.dateFormat("31/05/1988", null, "MM/dd/yyyy"); assertNotNull(response); response = CommonUtils.dateFormat("31/05/1988", "MM/dd/yyyy", null); assertNotNull(response); }