unittest-example-7

unittest-example-7.cs

// The Code which have issues before refactoring
// First: issue is passing the whole container which known as service locator pattern (Anti-Pattern) because it will 
// let us lost the value of mocking the real dependencies that the class is depend on and also the Auto Moqing with a tool like AutoMoqer
// will be no longer available.
// Second: There is an issue in LastPrintedBy as been shown below we violating the the law of demeter by calling object that we depend on
// then from it we call another object then another which made the testing difficult specially if those classes has no interface to implement which
// may let us swap the real objects with mocks easly.

public class PrintInvoiceCommand
    {
        private readonly Container _container;
        
        // Issue 1
        public PrintInvoiceCommand(
            Container container)
        {
            _container = container;
        }

        public void Execute(int invoiceId)
        {
            var invoice = _container
                .Get<IDatabase>()
                .GetInvoice(invoiceId);

            _container.Get<IInvoiceWriter>()
                .Write(invoice);
                // Issue 2
            invoice.LastPrintedBy = _container
                .Get<ISession>()
                .GetLogin()
                .GetUser()
                .GetUserName();

            _container
                .Get<IDatabase>()
                .Save();
        }
    }