### Question:
CommonUtils { public static boolean isEmailValid(String email) { Pattern pattern; Matcher matcher; final String EMAIL_PATTERN = "^[_A-Za-z0-9-\\+]+(\\.[_A-Za-z0-9-]+)*@" + "[A-Za-z0-9-]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$"; pattern = Pattern.compile(EMAIL_PATTERN); matcher = pattern.matcher(email); return matcher.matches(); } private  CommonUtils(); static ProgressDialog showLoadingDialog(Context context); static boolean isEmailValid(String email); static String getTimeStamp(); static Long getNegativeLong(int number);  }### Answer:
@Test public void isEmailValid_NoAtTheRate_False() { assertFalse(CommonUtils.isEmailValid(NO_AT_THE_RATE)); }
@Test public void isEmailValid_NoDomain_False() { assertFalse(CommonUtils.isEmailValid(NO_DOMAIN)); }
@Test public void isEmailValid_NoAtTheRateAndDomain_False() { assertFalse(CommonUtils.isEmailValid(NO_AT_THE_RATE_AND_DOMAIN)); }
@Test public void isEmailValid_UnAllowedSpecialCharacters1_False() { assertFalse(CommonUtils.isEmailValid(UN_ALLOWED_SPECIAL_CHARACTERS1)); }
@Test public void isEmailValid_UnAllowedSpecialCharacters2_False() { assertFalse(CommonUtils.isEmailValid(UN_ALLOWED_SPECIAL_CHARACTERS2)); }
@Test public void isEmailValid_UnAllowedSpecialCharacters3_False() { assertFalse(CommonUtils.isEmailValid(UN_ALLOWED_SPECIAL_CHARACTERS3)); }
@Test public void isEmailValid_CorrectInput_True() { assertTrue(CommonUtils.isEmailValid(CORRECT_INPUT)); }