Fighting Defect Clusters in Software Testing

Defects tend to cluster in some areas of the software under test. It may happen due to higher complexity, algorithms, or a higher number of integrations in a few constrained segments of the software.

These defect clusters can be tricky, both to find and to deal with. Testers need to be on constant alert for ways to isolate defect clusters and devise ways to overcome them, fight those defects and move on to new clusters.

In my article for Gurock blog, I discussed some ways to fight Defect Clusters in Software Testing:

Locating Defect Clusters

Most defects tend to cluster in certain areas of your software. It is one of the seven testing principles. Many testers intuitively know of these defect-prone areas, but we can still strive to be on the lookout for clusters of defects in a number of ways, like utilizing


Using metrics like defect density charts or module-wise defect counts, we can examine the history of defects that have been found and look for areas, modules, or features with higher defect density. This is where we should begin our search for defect clusters. Spending more time testing these areas may lead us to more defects or more complex use cases to try out.

For example, the chart below shows that Module 4 has the most defects, so it would be smart to continue concentrating on that module in the future.


Use the defect management system and the history of the software to go through older defects, and try to replicate them in the system. You will get to know the system’s history, where it broke and how it works now. You may learn a lot about the software and find many new areas to test.


A tester’s intuition, experience and history with the product is by far the best way to find defect clusters. Lessons learned by experienced teammates should be shared with new coworkers so that the knowledge can be passed on, utilized and improved upon by exercising these defect-prone areas with new perspectives.

Fighting Defect Clusters

Defect clustering follows the Pareto rule that 80% of the defects are caused by 20% of the modules in the software. It’s imperative for a tester to know which 20% of modules have the most defects so that the maximum amount of effort can be spent there. That way, even if you don’t have a lot of time to test, hopefully, you can still find the majority of defects.

Once you know the defect cluster areas, testers can focus on containing the defects in their product in a number of ways. Continue Reading—>

The Art of Bug Advocacy

Testers find defects and raise awareness about quality. What happens after the bugs are found can be any tester’s guess, though. Bugs may get delayed, postponed, go unnoticed or linger on due to lack of information.

In my article for Ranorex blog, I talk about how Testers need to champion the cause of their bugs in order to avoid unneeded delays in fixing defects that are important. At the same time, testers should maintain a distance to make it an impersonal and impartial experience. Testers need to master the art of bug advocacy!

Why is advocacy important?

Advocacy is basically pleading the case for a bug to be fixed. The testers who find the bugs are the ones who need to advocate for their bugs. It is important that they take a stand and voice their opinions.

Some bugs may not be deemed important from a business perspective, as they seem too small. But in reality, they may be blocking an important feature for a particular user group. On the other hand, some bugs may seem more critical than they truly are, and while fixing them may be important, it may not be the highest of priority.

Whatever the case, testers must aim to present the facts and data in such a way that decision-makers are able to make well-informed resolutions about the issue.

Communication is key

Advocating for anything is not a one-way street. It takes discussion, debate and reaching a consensus on key points to make a collective decision. This is where testers’ communication skill plays a key role. Testers need to have good communication, both verbal and written.

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Components of a Defect Management Software

 Since software developers and testers work together in the Agile and DevOps environments, it gets challenging to cope up with the increasing competition. Development teams work in collaboration with various stakeholders to make the most of the testing efforts. Defects in software applications are a norm, the sooner you realize that better it is. It is impossible to have a 100% defect/error-free software application, but experts work to make the most of their efforts. The current need for faster delivery and quality products calls for robust software testing solutions that can meet customer expectations.

A defect management system is a defect repository where all the defects appearing in a system are identified, recorded and assigned for rectification. This system includes defect management software and defect management tools to achieve projects efficiently. 

How Does Defect Management Work?

A defect management system works in a systematic manner, and records all the defects in the system without duplicating defects, and maintaining a log for future use too. There are different steps involved in the defect management that are explained below–

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