Software industry has grown at exponential rate in last few years. Demand of delivering high quality product rapidly increasing. In such situation, we Software Testers have to maintain the quality standards with latest techniques. It is very hazardous to wait for defects to occur at later stage. In Medical Science there is a principle, “Prevention is Better than Cure”; same applies to Software Development Life Cycle. Hence, it is very necessary to control Defect Detection by removing them before they appear in the system. Such prevention techniques help us to build a high quality product and also reduce the project cost.

In this article we are going to discuss about what is defect detection and defect prevention. We will also throw some light on the role of a Software Tester to achieve the best use of these techniques.

A Software Defect is the deviation between the expected and actual result. Anything that prevents the software to perform the action or leads the application to produce result we do not desire is a Bug/Defect.  Testing team applies number of methods and testing types may be applied to detect defects during software testing life-cycle.


What is Defect Prevention?

Defect Prevention is a process to identify the root cause of defects and establish the process to avoid defects surfacing. By focusing on Defect Prevention, we can work on improving the quality of the Software from very earlier stage.

Testers review requirement specification documents, try to understand the requirement from end user perspective. During this activity lots of misleading requirements are cleared. This stage is not only for Software Testers. Developers also play a key role by participating in activities like – Code Review/ Static Code Analysis, Unit Testing etc.

What is Defect Detection?

Testers, with complete understanding of application under test, play a key role in Defect Detection process. Well planned testing activities are carried out in order to find as many defects as possible. These activities include various testing types e.g System Testing, End to End Testing, Regression-Retesting, Exploratory Testing etc. To calculate the effectiveness of this phase there is a parameter we must calculate: DDP(Defect Detection Percentage).

Defect Detection Percentage(DDP)

DDP tells you the effectiveness of Testing. We can measure DDP as the ratio of defects captured prior to release by Testing Team and after the release by Customer. DDP is often called as DRE(Defect removal efficiency).

DDP = [Number of defects at the moment of software version release / Total number of defects(raised by internal testing team + customer)] X 100%

For Example, suppose 70 defects were found during testing phase & 20 defects found by customer. The DDP would be [100/(100+20)]X100=83.3%

Below image illustrates you the phases involved in Defect Prevention & Defect Detection.

Defect Detection

Now you know, earlier the defect detected higher the DDP goes. Hence, defect prevention is a valuable investment which makes your life more easier during defect detection phase. Here are some more links you must visit,

What is Defect Life cycle in Software Testing?

10 Tips to write a complete Bug Report in Software Testing

Don’t forget to share your feedback. Happy Testing!!


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