how are the tests performed in this question?

The EmailValidator class has the isValidEmail () function, which produces a true answer when email addresses are valid and false if invalid. To test the accuracy of this function, you are asked to produce 7 different test functions. These test functions are as follows; The correct e-mail address, subdomain e-mail address .com-free e-mail address, invalid e-mail address, e-mail address without user name, blank entry and null value entries must be present.

public class EmailValidator{
    public static final Pattern EMAIL_PATTERN = Pattern.compile(
       "[a-zA-Z0-9\\+\\.\\_\\%\\-\\+]{1,256}"+"\\@"+
       "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}"+"("+"\\."+
       "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,25}"+")+");
    public static boolean isValidEmail(CharSequence email){
       return email != null &&;
EMAIL_PATTERN.matcher(email).matches();
 }
}