public async void DoesValidatorAllowCorrectRequestWithoutClassId()
        {
            var db        = new FakeDbContext();
            var validator = new GetSubscribersCountValidator(db);

            var request = new GetSubscribersCount();

            var result = await validator.ValidateAsync(request);

            result.IsValid.Should().BeTrue();
        }
        public async void DoesValidatorPreventFromGettingCountFromNonExistingClass()
        {
            var db        = new FakeDbContext();
            var validator = new GetSubscribersCountValidator(db);

            var request = new GetSubscribersCount
            {
                ClassId = "non-existing-class"
            };

            var result = await validator.ValidateAsync(request);

            result.IsValid.Should().BeFalse();
            result.Errors.Should().HaveCount(1).And.ContainSingle(x => x.ErrorCode == "AsyncPredicateValidator" & x.ErrorMessage == "Mentioned class must already exist.");
        }