dcomartin

public async Task<IActionResult> OnPost(CatalogItemViewModel productDetails)
{
    if (productDetails?.Id == null)
    {
        return RedirectToPage("/Index");
    }

    await SetBasketModelAsync();

    var result = await _basketService.AddItemToBasket(BasketModel.Id, productDetails.Id, productDetails.Price, productDetails.Quantity);

dcomartin

public interface IBasketService
{
    Task<Either<int, QuantityValidationError>> AddItemToBasket(int basketId, int catalogItemId, decimal price, int quantity = 1);
}

public class QuantityValidationError
{
    public string Message { get; set; }

    public QuantityValidationError(string message)

dcomartin

public interface IBasketService
{
    Task<int> AddItemToBasket(int basketId, int catalogItemId, decimal price, int quantity = 1)
}

public class BasketService : IBasketService
{
    private readonly IAsyncRepository<Basket> _basketRepository;

    public BasketService(IAsyncRepository<Basket> basketRepository)

dcomartin

public class Either<TLeft, TRight>
{
    private readonly TLeft _left;
    private readonly TRight _right;
    private readonly bool _isLeft;

    public Either(TLeft left)
    {
        _left = left;
        _isLeft = true;

dcomartin

public class CustomerOrder : IOrder
{
    private readonly CatalogContext _dbContext;

    public CustomerOrder(CatalogContext dbContext)
    {
        _dbContext = dbContext;
    }

    public string GetShippingAddress(int orderId)

dcomartin

public interface IOrder 
{
  string GetShippingAddress(int orderId);
}

dcomartin

public interface Basket
{
  int Additem(int basketId, int catalogItemId, decimal price, int quantity);
}

dcomartin

public class ScopedLifetimeTest
{
    [Fact]
    public async Task ShouldShitTheBed()
    {
        var serviceCollection = new ServiceCollection();
        serviceCollection.AddScoped<ClassA>();
        serviceCollection.AddScoped<ClassB>();
        serviceCollection.AddScoped<ClassC>();
        var provider = serviceCollection.BuildServiceProvider();

dcomartin

public class ClassC
{
    private string? _state;

    public async Task<int> NotThreadSafe(string state)
    {
        _state = state;

        // Delay this Task so we can end up having ClassB change the state before we return the length
        if (state.Length > 0)

dcomartin

public class ClassA
{
    private readonly ClassB _classB;
    private readonly ClassC _classC;

    public ClassA(ClassB classB, ClassC classC)
    {
        _classB = classB;
        _classC = classC;
    }