Agile India.

Starting with the obvious forms of duplication like Cltr+C & Cltr+V pattern to more subtle forms of duplication:

• Literal Duplication. Ex: Same for loop in 2 places
• Semantic Duplication: In essence the code does the same thing, but is syntactically different. Again there are sub-levels:
  • 1st Level: Ex: for and foreach loop

     for(int i : someList)
        stack.push(i);

    v/s

     for(int i=0; i < someList.size(); i++)
        stack.push(someList.get(i));

  • 2nd Level: Ex: Looping over an array of elements instead of each element in a different line

     stack.push(1);
    stack.push(3);
    stack.push(5);
    stack.push(10);
    stack.push(15);

    v/s

     for(int i : asList(1,3,5,10,15))
        stack.push(i);

  • 3rd Level: Ex: Loop v/s Recursion
• Data Duplication. Ex: Some constant declared in 2 classes (test and production)
• Structural Duplication: Ex: Parallel Inheritance Hierarchy
• Conceptual Duplication: Ex: 2 Algos to Sort elements (Bubble sort and Quick sort)
• Representational Knowledge Duplication: Commonly know at WET (violation of DRY - Don’t Repeat Yourself)
• Duplication of logical steps: Same set of steps repeat in different scenarios. Ex: Same set of validations in various points in your applications
• Duplication of statement fragments: Same sections of a statement repeating. Ex:

   Assert.IsTrue(response.HasHeader);
  Assert.IsTrue(response.HasMessageId);
  Assert.IsTrue(response.Has("X-SenderIP: " + senderIp));
  Assert.IsTrue(response.Has("X-SenderDomain: " + senderDomain));
  Assert.IsTrue(response.Has("X-recipientDomain: " + recipientDomain));
  Assert.IsTrue(response.Has("X-SPF: " + spfValue));
  Assert.IsTrue(response.Has("X-1stClassification: " + firstClassificationResult));
  Assert.IsTrue(response.Has("X-2ndClassification: " + secondClassificationResult));
  Assert.IsTrue(response.Has("X-3rdClassification: " + thirdClassificationResult));
  Assert.IsTrue(response.Has("X-MANUALLY-CLASSIFIED: " + manuallyClassified));

  Once we clean this up, it might look like:

   lets.checkThat(response).HasHeader.HasMessageId.Has + "X-SenderIP" = senderIp + "X-SenderDomain" = senderDomain
          + "X-recipientDomain" = recipientDomain + "X-SPF" = spfValue + "X-1stClassification" = firstClassificationResult
          + "X-2ndClassification" = secondClassificationResult + "X-3rdClassification" = thirdClassificationResult + "X-MANUALLY-CLASSIFIED" = manuallyClassified;

Thanks to Corey Haines and the folks who participated in the Biggest Stinkers session @ the Simple Design and Testing Conference 2009. Most of this information was discussed during that session.

This entry was posted on Wednesday, October 21st, 2009 at 10:20 pm and is filed under Design. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.