public void ShouldHaveErrorWhenSubjectIsNullOrEmpty()
        {
            var model = new EditForumTopicModel
            {
                Subject = null
            };

            _validator.TestValidate(model).ShouldHaveValidationErrorFor(x => x.Subject);
            model.Subject = string.Empty;
            _validator.TestValidate(model).ShouldHaveValidationErrorFor(x => x.Subject);
        }