Kata2: The Decorator Pattern


This the second part of the series of Coding Kata’s. Here we’ll explore the Decorator pattern.

This is the user story:

You need to send alerts to your customers when a new product is available. 
An Alert is represented by the Alert Class:

public class Alert
      public String DestinationAddress { get; set; }
      public String SenderAddress { get; set; }
      public String Content { get; set; }
      public string Log { get; set; }

Classes used to send the Alerts implement the following interface:

public interface ISender
        void Send(Alert alert);


  • Create an Alerter class that send the appropriate alerts.  
  • Alerts are always send by e-mail.
  • Customers can also subscribe to receive alerts via sms and/or through messenger. 
  • Use the Decorator pattern to configure the Alerter

    You do not need to use real infrastructure code to send the alert, just append a string that contains the Sender through which the message was send.
    ->Append the following text to the Alert.Log when the message is send by:

  • e-mail      : “Message was send by e-mail”
  • sms         : “Message was send by sms”
  • messenger: “Message was send by messenger”


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