Differentiating between severity and priority of bug is really a very tedious thing to decide. We testers are quite familiar with Bug and its status and we manage its status across complete software testing life cycle. Bug severity and priority is always a kind of question hanging before most of the QA.
Most of the time we testers perceive priority and severity pretty same thing. Because lot of bug tracking tools have permanently removed the severity field and have allotted all severity fields to priorty and one of such tool is Jira Then why people in interviews asks ” difference between Priority and Severity”. So let me provide you elaborative and descriptive definition of these two terms. For better understanding, I will throw some examples as well. So be ready to catch it to crack your next interview.
Priority: Priority is related to business and revenue. So here i will say ” Priority of a bug is defined by its impact on business. It mean any defect or bug which is going to increase business profit or reduce the same. it means such tickets will be picked on priority and for this more and more business management people will get involved.( It includes Manager, Architect, team lead).
Severity: Severity of a bug is decided by its impact on application and theoretically it is decided by tester.
Type of Severity
1- Blocker: If application is not being started on clicking on its icon, screen of application is freezing and crashes are coming or UI rendering of application or some data corruption.
2- Critical: When main functionality is not working and there is some logical error. Which is going to produce wrong result. Such defects/bug will be marked as Ciritcal.
3- Major : If performance of main functionality is not good and secondary functionality is not working and giving wrong result
4- Normal: Minor functionality is not working properly
5- Minor: When minor functionality is being impacted due to some intermittent errors and some spelling mistakes
Types of Priority
Immediate(P1): Must be fixed on immeditate effect. All critical and major severity based bug normally fall in this catagory
High: Highly desirable and schedules, Bug with major and normal severity fall in this category
Medium: This is desirable to be fixed but not scheduled. We can also say “if time permits then fixed it” .Few normal severity bugs fall in this category
Low: Not likely to be fixed and bug with minor severity fall in this category
So why not we are going to learn it with some live example
1- High Priority and High Severity: Suppose someday gmail is going down and no one is able to access it across the world. Then this is tarnish the name and reputation of google along with monetory loss. So this will be of high priority and high severity
2- High Priority and low severity : One morning when you open google.com and find that spelling on screen is coming something like Fuugle. this might shock you and intend you to leave the site immediately due to fear of malware/phishing site . This will give big blow to google search, but search is still working. So in this case, bug will be of high priority and low severity
3- Low priority and high severity : Let’s you calculator starts showing wrong value when you are using 18 digits for calculation. But most of the common user never goes to such extent. So this might be taken as low priority but calculation mistake is very severe, so severity of this ticket or defect will be high.
4- Low priority and Low severity: Suppose, somewhere in any advertisement, there is a grammatical mistake, Which can be ignored by all. So this will be the example of low priorty and low severity.