public async Task GetCustomerWishlistAsync_ShouldReturnList_WhenCustomerDoesExist()
{
//Arrange
_customerService.GetCustomerAsync(customerId).Returns(existingCustomer);
List <WishListProduct> list = new List <WishListProduct>();
list.Add(new WishListProduct());
_wishlistRepository.GetCustomerWishlistAsync(customerId).Returns(list);
//Act
var sut = new WishlistService(_productRest, _customerService, _wishlistRepository);
var products = await sut.GetCustomerWishlistAsync(customerId);
//Assert
Assert.NotNull(products);
Assert.Single(products);
}