public void AllFavoriteShouldReturnAllFavoriteProducts() { var options = new DbContextOptionsBuilder <XeonDbContext>() .UseInMemoryDatabase(databaseName: "All_Favorites_Database") .Options; var dbContext = new XeonDbContext(options); var username = "******"; dbContext.Users.Add(new XeonUser { UserName = username }); var products = new List <Product> { new Product { Name = "USB" }, new Product { Name = "Phone Samsung" }, new Product { Name = "Phone Nokia" }, new Product { Name = "Phone Iphone" }, new Product { Name = "Tablet Galaxy" } }; dbContext.Products.AddRange(products); dbContext.SaveChanges(); var favoriteService = new FavoritesService(dbContext); foreach (var product in products.Take(3)) { favoriteService.Add(product.Id, username); } var favoriteProducts = favoriteService.All(username); Assert.Equal(3, favoriteProducts.Count()); }