back to BLOG

Why Do Bugs Appear in Clusters?

Learn why it is common for bugs to appear in clusters, and what teams can do to help minimize this occurrence.

December 15, 2022
Tamas Cser

Elevate Your Testing Career to a New Level with a Free, Self-Paced Functionize Intelligent Certification

Learn more
 Learn why it is common for bugs to appear in clusters, and what teams can do to help minimize this occurrence.
Defect clustering is the concept that defects in software often occur in clusters, rather than being evenly distributed throughout the software.

This means that there are often groups of defects that are found together in specific parts of the software, rather than individual defects being isolated from each other.

Understanding and addressing the reasons for defect clustering can help software testers to identify and fix defects more effectively.  Here are 5 reasons why this may be a common occurrence:

  1. Similar code:
    If different parts of a software program share similar code, then a bug in one part of the code is likely to cause similar bugs in other parts of the code that use the same code.
  1. Common dependencies:
    If different parts of a software program rely on the same external libraries or other dependencies, then a bug in one of those dependencies is likely to cause similar bugs in the parts of the software that depend on it.
  1. Shared data:
    If different parts of a software program access the same data, then a bug in one part of the program that affects the data is likely to cause similar bugs in other parts of the program that access the same data.
  1. Complex interdependencies:
    If a software program has a complex network of interdependencies between its different parts, then a bug in one part of the program is likely to have cascading effects that cause similar bugs in other parts of the program.
  1. Human error:
    If multiple people are working on different parts of a software program, then it is possible that the same human error (such as a misunderstanding of the requirements or a mistake in the code) will be introduced in multiple places in the program. This can cause similar bugs to occur in clusters.

Shift Left and Catch Bugs Early

In all cases where bugs may arise, whether clustered or not, the importance of starting testing activities as early as possible in the development process is imperative to on-time releases. This means that testing begins even before the code has been written, and continues throughout the development process. By starting testing early, otherwise known as Shift left Testing, it is possible to catch bugs before they have a chance to become more deeply embedded in the code.

Test Continuously

Shift left testing also emphasizes the importance of continuous testing, which means that testing is performed at every stage of the development process, not just at the end. This means that bugs and other defects can be caught and fixed as soon as they are introduced and before they have a chance to cause problems.

Involve All Team Members

Shift left testing also emphasizes the importance of involving all team members in the testing process. This means that developers, testers, and other team members all work together to identify and fix bugs caused by similar code, shared data, interdependencies and human error.