public async Task GetTopAsyncTest()
        {
            var tops = (await _hashTagRepository.GetTopAsync(3)).ToList();

            Assert.AreEqual(3, tops.Count());
            Assert.AreSame(hashTag2, tops[0]);
            Assert.AreSame(hashTag1, tops[1]);
            Assert.AreSame(hashTag3, tops[2]);
        }
        public async Task <IEnumerable <HashTag> > GetTopAsync(int amount)
        {
            ServiceHelpers.CheckValidId(amount);

            return(await _repository.GetTopAsync(amount));
        }