public void Test_UserNameMustExistValidator_Valid()
        {
            var value = "test";
            var validator = new UserNameMustExistValidator(new FakeUserService());
            var results = validator.Validate(new PropertyValidatorContext("test", value, "test", "value"));

            Assert.IsEmpty(results.ToList());
        }
        public void Test_UserNameMustExistValidator_NotValid()
        {
            var value = "test2";
            var validator = new UserNameMustExistValidator(new FakeUserService());
            var results = validator.Validate(new PropertyValidatorContext("test", value, "test2", "value"));

            foreach (var result in results)
            {
                Assert.AreEqual(Errors.UserNameNotFound, result.ErrorMessage);
            }
        }