Defect Severity in Software Testing

Defect Severity in Software Testing
Flaws or defects in any system can be damaging to its success. At the same time, each and every defect is not as detrimental as the next one. Through this article, we shall try and assimilate how the defect impacts the components of software by studying about Defect Severity.

What Is a Defect?

A defect is a shortcoming, an imperfection or a flaw in any object or system.

Meaning of Defect Severity

In terms of software testing, Defect Severity is the impact that a defect has on either the development or execution of any program. It is the degree of impact that a defect has, on the application. The higher the degree of impact or severity the more detrimental the error will be. The honest opinion is that Defect Severity in software testing depends on how important the tested function is.

Who Tests For Defects

Every software undergoes comprehensive testing before it can be launched. The purpose of these various tests is to find and remove defects. When it comes to testing, it can be done by either the code developers themselves or the testers, as the case may be.

Types of Defects

Defects are classified into 4 main types based on the severity of their impact. These are:

  • Critical – These are those errors which result in complete failure, for example, unable to load software, etc. Such errors prevent any further testing as they do not have a workaround. Symbolically, critical errors are denoted by S1.
  • Major – A major defect is that which collapses or crashes the system and yet there are a few functionalities that remain operable. The workaround in such cases is not impossible but it is very difficult. Such errors are denoted by the symbol S2.
  • Minor – Such defects have an impact on the less important data and minor functions. It can cause some malfunction but will still keep the software up and running. The workaround is easy and obvious. Minor defects are denoted by the symbol S3.
  • Trivial - These errors do not relate to the data or working of the software. In fact, trivial errors are those that relate to the look and feel of the program. These errors do not cause malfunctions by impacting any data or function. Trivial errors are denoted by the symbol S4.

Caution To Be Exercised While Testing Defect Severity

Great caution needs to be exercised while checking for the severity of a defect. This is because even a minor oversight can make a critical error trivial and vice-versa. Also, when it comes to the war of words between the developers and the testers, it has often been seen that the developers do not agree with the findings of the testers in terms of the impact that a defect can have. This problem can, however, be overcome by setting some mutually agreed upon standards.


Calculating the Defect severity is the best way of prioritizing corrective action and its implementation. Obviously, a critical error needs to be addressed first and foremost, subsequently moving down the line.