public void validating_FirstName()
 {
     try
     {
         UserValidationUsingLambda validate = new UserValidationUsingLambda();
         bool result = validate.firstName_Validation("bh");
     }
     catch (UserRegistrationExceptions e)
     {
         Assert.AreEqual("firstName should be min of 3 char", e.Message);
     }
 }