public async Task When2UsersRateForTheSameQuestionTheAverageVoteShouldBeCorrect()
{
var list = new List <Rating>();
var mockRepo = new Mock <IRepository <Rating> >();
mockRepo.Setup(x => x.All()).Returns(list.AsQueryable());
mockRepo.Setup(x => x.AddAsync(It.IsAny <Rating>())).Callback(
(Rating rating) => list.Add(rating));
var service = new RatingsService(mockRepo.Object);
await service.SetRatingAsync(2, "Niki", 5);
await service.SetRatingAsync(2, "Pesho", 1);
await service.SetRatingAsync(2, "Niki", 2);
mockRepo.Verify(x => x.AddAsync(It.IsAny <Rating>()), Times.Exactly(2));
Assert.Equal(2, list.Count);
Assert.Equal(1.5, service.GetAverageRatings(2));
}