### Question:
Utilities { public static boolean validateEmail(String email) { String regex = "^[\\w!#$%&'*+/=?`{|}~^-]+(?:\\.[\\w!#$%&'*+/=?`{|}~^-]+)*@(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,6}$"; Pattern pattern = Pattern.compile(regex); Matcher matcher = pattern.matcher(email); return matcher.matches(); }  static boolean validateEmail(String email); static String toTitleCase(String s);  }### Answer:
@Test void testEmail() { assertFalse(Utilities.validateEmail("halo dunia!")); assertFalse(Utilities.validateEmail("abc123")); assertFalse(Utilities.validateEmail("abc123@abc.com@")); assertTrue(Utilities.validateEmail("abc123@abc.com")); }