无法将模拟程序的设置方法传递给对象列表C＃

Question

While mocking I ran into some problems.

 private Mock<IPaymentHandler> _mockRecurringPaymentHandler;
 private Mock<IPaymentHandler> _mockRecurringPaymentFailedHandler;
 private IEnumerable<IPaymentHandler> _paymentManagers;

_mockRecurringPaymentHandler = new Mock<IPaymentHandler>();
_mockRecurringPaymentFailedHandler = new Mock<IPaymentHandler>();

_paymentManagers = new List<IPaymentHandler>
{
    _mockRecurringPaymentHandler.Object,
    _mockRecurringPaymentFailedHandler.Object
};

_sut = new PaypaIIpnManager(
    _paymentManagers,
    _mockLogger.Object
    );

And when lately I try to setup a method for mockRecurringPaymentHandler , eg below:

_mockRecurringPaymentHandler.Setup(method => method.GetPaymentType()).Returns("GFDGDFGDFG");

It doesn't work. It works only if I do it before passing it to list. Why does this have such behavior?

public PaypaIIpnManager(
            IEnumerable<IPaymentHandler> paymentHandlers,
            ILoggerService<PaypaIIpnManager> logger)
        {
            _handlersDic = RegisterStrategy(paymentHandlers);
            _logger = logger;
        }

protected Dictionary<string, IPaymentHandler> RegisterStrategy(IEnumerable<IPaymentHandler> paymentHandlers)
        {
            var dic = new Dictionary<string, IPaymentHandler>();

            foreach (var handler in paymentHandlers)
            {
                var paymentType = handler.GetPaymentType();

                dic.Add(paymentType, handler);
            }

            return dic;
        }

Answer 1

Remember unit testing works on a concept of AAA --- Arrange, Act and Assert. Until you don't arrange the things appropriately, act does not work as required.

So here when PaypaIIpnManager constructor is invoked then it calls your RegisterStrategy which invokes GetPaymentType for your mocked handler. Since before invoking the constructor, the GetPaymentType is not setup that's why in your test the setup method GetPaymentType is not called. So here, you should define the GetPaymentType Setup before you call the constructor.