unittest-example-10

unittest-example-11.cs

// The solution is to refactor the GOF class to be instance class and let it use interface to make it easy to inject
// Then use the IOC/DI singleton way to ensue using only one instance of the object.

// The Interface
public interface ISecurity
    {
        string GetUserName();

        bool IsAdmin();
    }
 // Security class after refactoring to be instance class
  public class Security : ISecurity
    {
        private string _userName;
        private bool _isAdmin;

        public void SetUser(string userName, bool isAdmin)
        {
            _userName = userName;

            _isAdmin = isAdmin;
        }

        public string GetUserName()
        {
            return _userName;
        }

        public bool IsAdmin()
        {
            return _isAdmin;
        }
    }
   // Use the Security class in the service class we want to test:
   public class PrintInvoiceCommand
    {
        private readonly IDatabase _database;
        private readonly ISecurity _security;
        private readonly IInvoiceWriter _writer;

        public PrintInvoiceCommand(
            IDatabase database,
            ISecurity security,
            IInvoiceWriter writer)
        {
            _database = database;
            _security = security;
            _writer = writer;
        }

        public void Execute(int invoiceId)
        {
            var invoice = _database.GetInvoice(invoiceId);

            if (!_security.IsAdmin())
                throw new UserNotAuthorizedException();

            _writer.Print(invoice);

            invoice.LastPrintedBy = _security.GetUserName();

            _database.Save();
        }
    }
   // Ensure DI Singleton for the security class:
   public class Program
    {
        static void Main(string[] args)
        {
            var invoiceId = int.Parse(args[0]);

            var container = new StandardKernel();

            container.Bind(p =>
            {
                p.FromThisAssembly()
                    .SelectAllClasses()
                    .BindDefaultInterface();
            });

            container.Bind<ISecurity>()
                .To<Security>()
                .InSingletonScope();

            var command = container.Get<PrintInvoiceCommand>();

            command.Execute(invoiceId);
        }
    }