public void ValidateObject_OverrideRole_ExistingValidationRuleExceptionThrown() { var user = new User("Robert"); var error = user["Name"]; Assert.IsNotNull(error, "Default validation"); Assert.Throws<ExistingValidationRuleException>(() => { user.AddValidationRule(() => user.Name , () => !user.Name.ToLower().StartsWith("a") , "Oops"); }); }