### Question:
CommonUtil { public static boolean isBlank(String str) { if (str == null || str.length() == 0) return true; return false; } private  CommonUtil(); static boolean isEmpty(List list); static boolean isBlank(String str); static String sanitize(String v); static String DateToDayString(Date date); static Date dayToDate(String day); static String convertToString(List<String> list); static Map convertToMap(Object object); static List<String> removeStringFromItems(List<String> list, String toRemove); static Integer determinePriceCatForCPM(double price); static Integer determinePriceCatForCPC(double price); static Integer determinePriceCatForCPD(double price); static Integer determinePriceCatForCPT(double price); static Integer determinePriceCat(double price, TargetingChannel.PriceModel priceModel); static String removeEscapingCharacters(String str); static boolean equalNumbers(double d1, double d2);  }### Answer:
@Test public void isBlank() { String s = null; assertTrue(CommonUtil.isBlank(null)); assertTrue(CommonUtil.isBlank(s)); s = "abc"; assertFalse(CommonUtil.isBlank(s)); s = ""; assertTrue(CommonUtil.isBlank(s)); }