unittest-example-10

unittest-example-10.cs

// This class will be used to create a simple GOF singletone object.

public class Security
    {
        private static Security _instance;
        private string _userName;
        private bool _isAdmin;

        public static Security GetInstance()
        {
            if (_instance == null)
                _instance = new Security();

            return _instance;            
        }

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

            _isAdmin = isAdmin;
        }

        public string GetUserName()
        {
            return _userName;
        }

        public bool IsAdmin()
        {
            return _isAdmin;
        }
    }
    
    // The issue shown here while we used GOF singleton object Security.GetInstance(); which will be hard to test.
     public class PrintInvoiceCommand
    {
        private readonly IDatabase _database;
        private readonly IInvoiceWriter _writer;

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

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

            var security = Security.GetInstance();

            if (!security.IsAdmin())
                throw new UserNotAuthorizedException();
            
            _writer.Print(invoice);

            invoice.LastPrintedBy = security.GetUserName();

            _database.Save();
        }
    }