public async Task GetSingle_Success(int id)
{
// Arrange
var dbContext = _fixture.Context;
var mapper = MapperMock.Get();
var user1 = NewDatas.NewUser();
var user2 = NewDatas.NewUser();
var product = NewDatas.NewProduct();
var rating = NewDatas.NewRating();
rating.User = user1;
rating.Product = product;
var rating1 = NewDatas.NewRating();
rating1.User = user2;
rating1.Product = product;
dbContext.Products.Add(product);
await dbContext.SaveChangesAsync();
dbContext.Users.AddRange(user1, user2);
await dbContext.SaveChangesAsync();
dbContext.Ratings.AddRange(rating, rating1);
await dbContext.SaveChangesAsync();
var ratingsService = new RatingService(dbContext);
var ratingsController = new RatingsController(ratingsService, mapper);
// Act
var result = await ratingsController.GetRatingByProductId(id);
// Assert
var ratingResult = Assert.IsType <OkObjectResult>(result.Result);
Assert.NotNull(ratingResult.Value);
}