Software Testing: Difference Between Severity And Priority

Testing is a process of executing a program or an application with the intent of finding errors or we can say that testing is the process of establishing confidence that a program does what it is supposed to do.

The most common interview question in testing field is, Explain the difference between Severity and Priority with examples.

Severity and Priority are two distinct terms, lets discuss it.

What is Severity

Severity describes how the defect is impacting the functionality of the software or a product under test. It is a parameter set by the tester at the time of opening a defect to denote the implication of the defect on the system- how critical the defect is and its impact on the whole system's functionality.

Different organizations have different tools to use for defects, but on a generic level following are the levels of severity a tester can assign to a defect at the time of opening a defect:

  • Critical/Show Stopper Severity: Critical severity means the major functionality is completely down due to which tester cannot do further testing.

  • Major/Severe/High Severity: Major severity means the major functionality of the application is not working but the tester is able to test the application.

  • Moderate/Normal/Medium Severity: Moderate severity are the logical defects which does not block any functionality and cause some undesirable behavior but the system is still functional.

  • Low/Minor Severity: Minor severity occurs when there is almost no impact to the functionality which does not harm to application under test but the defects should be corrected.

What is Priority

Priority describes the importance of the defect and when it should be fixed. It states the order in which the defect should be fixed. Higher the priority, sooner the defect should be resolved. The defect which leaves the software/application unstable are given as higher priority over the defects that cause a small functionality of the software/application to fail.

Like severity, Priority also has different types depending upon the basis of business impact, development efforts and more.

  • High: A defect having high business value where end user cannot work unless the defect gets fixed. This priorities defect should be fixed on urgent basis.

  • Medium: End user can work using workaround but some functionalities of the software/application end user cannot use. This priorities defect may be fixed after the release.

  • Low: This defect may or may not be fixed and can be scheduled when time is available.

Tips for determining Severity of a Defect

  • Decide the frequency of occurrence: A minor defect can also be more severe if the occurrence of a minor defect is frequent in the application, therefore the impact of defect is higher.

  • Identity the defect: Identifying the defect helps to find out its depth of impact. Make sure that the defect occurs only with particular sequence of operations which causes the defect.

Answer yourself the following questions before determining the severity

The following questions helps us to decide the measure of severity,

  1. Does the system allow me to work even after defect occurs?
  2. Does the system recover from the defect?
  3. Did I check whether the same defect is reflected in all other related sections or entire system?
  4. Can I be able to replicate the defect in some other system having same configuration (OS, browsers, etc) as that of the system where I found the defect?
  5. Can I be able to repeat the defect in other configurations also?
  6. Does the defect affect all categories of user or only a particular category?
  7. How frequently the defect occurs?
  8. What are the inputs (scenario) which causes the defect to occur?

The level of severity increases if the answer for the above questions is 'Yes'.

Difference between Severity and Priority

PrioritySeverity
Priority defines the order in which the defect should be resolved by the developerSeverity defines the degree of impact that a defect has on the product
Priority is categorized into following types
  • High
  • Medium
  • Low
Severity is categorized into following types
  • Critical
  • Major
  • Moderate
  • Low
Priority is associated with schedulingSeverity is associated with functionality
Priority indicates how soon the bug should be fixedSeverity indicates the seriousness of the defect on the product functionality
High priority and low severity status indicates that the defect have to be fixed on immediate basis which is not affecting the applicationHigh severity and low priority status indicates that the defect have to be fixed but not on immediate basis.
Priority is given by Test lead or project managerSeverity is given by the tester

Examples of defects with priority and severity

  • High priority, high severity: Any defect which causes tester to not continue the testing of software/application or causes a severe system failure fall under this category. For example, upon login to system "Run time error" displayed on the page, so due to which the tester is not able to perform further testing process.

  • High priority, low severity: The defects which have to be fixed but do not affect the software/application fall under this category. For example, Spelling mistake in the name of the company on the homepage is a high priority defect. In terms of the functionality it is not breaking anything but is making a bad impact on the reputation of the company.

  • High severity, low priority: The defects which have to be fixed but not immediately falls under this category. For example, Application is crashed in a uncommon scenario which is impacting major functionality of system so the severity of defect is high but as it is a uncommon scenario so many of the user may not be seeing this page so we can mark this as low priority.

  • Low severity, low priority: This defects occur when there is no functionality break but still the application is not meeting the standards. For example, spelling mistake in the confirmation error message.

Conclusion

While opening a new defect it is the responsibility of the tester to assign the right severity and priority to the defects.

I hope with the help of this article you came to understand the most common interview questions in testing-'Difference between Severity and Priority'. 

Your valuable comments are most welcomed.