Tuesday, July 1, 2008

Bug Life Cycle

What is Bug/Defect?

Simple Wikipedia definition of Bug is: “A computer bug is an error, flaw, mistake, failure, or fault in a computer program that prevents it from working correctly or produces an incorrect result. Bugs arise from mistakes and errors, made by people, in either a program’s source code or its design.”

Other definitions can be:
An unwanted and unintended property of a program or piece of hardware, especially one that causes it to malfunction.
(or)
A fault in a program, which causes the program to perform in an unintended or unanticipated manner.

Lastly the general definition of bug is: “failure to conform to specifications”.

If you want to detect and resolve the defect in early development stage, defect tracking and software development phases should start simultaneously.

Life cycle of Bug:

1) Log new defect
When tester logs any new bug the mandatory fields are:
Build version, Submit On, Product, Module, Severity, Synopsis and Description to Reproduce.

In above list you can add some optional fields if you are using manual Bug submission template:
These Optional Fields are: Customer name, Browser, Operating system, File Attachments or screenshots.

The following fields remain either specified or blank:
If you have authority to add bug Status, Priority and ‘Assigned to’ fields them you can specify these fields. Otherwise Test manager will set status, Bug priority and assign the bug to respective module owner.

when you consider the significant steps in bug life cycle you will get quick idea of bug life. On successful logging the bug is reviewed by Development or Test manager. Test manager can set the bug status as Open, can Assign the bug to developer or bug may be deferred until next release.

When bug gets assigned to developer and can start working on it. Developer can set bug status as won’t fix, Couldn’t reproduce, Need more information or ‘Fixed’.

If the bug status set by developer is either ‘Need more info’ or Fixed then QA responds with specific action. If bug is fixed then QA verifies the bug and can set the bug status as verified closed or Reopen.

Bug status description:
These are various stages of bug life cycle. The status caption may vary depending on the bug tracking system you are using.

1) New: When QA files new bug.

2) Deferred: If the bug is not related to current build or can not be fixed in this release or bug is not important to fix immediately then the project manager can set the bug status as deferred.

3) Assigned: ‘Assigned to’ field is set by project lead or manager and assigns bug to developer.

4) Resolved/Fixed: When developer makes necessary code changes and verifies the changes then he/she can make bug status as ‘Fixed’ and the bug is passed to testing team.

5) Could not reproduce: If developer is not able to reproduce the bug by the steps given in bug report by QA then developer can mark the bug as ‘CNR’. QA needs action to check if bug is reproduced and can assign to developer with detailed reproducing steps.

6) Need more information: If developer is not clear about the bug reproduce steps provided by QA to reproduce the bug, then he/she can mark it as “Need more information’. In this case QA needs to add detailed reproducing steps and assign bug back to dev for fix.

7) Reopen: If QA is not satisfy with the fix and if bug is still reproducible even after fix then QA can mark it as ‘Reopen’ so that developer can take appropriate action.

8 ) Closed: If bug is verified by the QA team and if the fix is ok and problem is solved then QA can mark bug as ‘Closed’.

9) Rejected/Invalid: Some times developer or team lead can mark the bug as Rejected or invalid if the system is working according to specifications and bug is just due to some misinterpretation.

Bug and Statuses Used During A Bug Life Cycle
The main purpose behind any Software Development process is to provide the client (Final/End User of the software product) with a complete solution (software product), which will help him in managing his business/work in cost effective and efficient way. A software product developed is considered successful if it satisfies all the requirements stated by the end user.

Any software development process is incomplete if the most important phase of Testing of the developed product is excluded. Software testing is a process carried out in order to find out and fix previously undetected bugs/errors in the software product. It helps in improving the quality of the software product and make it secure for client to use.

What is a bug/error?
A bug or error in software product is any exception that can hinder the functionality of either the whole software or part of it.

How do I find out a BUG/ERROR?
Basically, test cases/scripts are run in order to find out any unexpected behavior of the software product under test. If any such unexpected behavior or exception occurs, it is called as a bug.

What is a Test Case?
A test case is a noted/documented set of steps/activities that are carried out or executed on the software in order to confirm its functionality/behavior to certain set of inputs.

What do I do if I find a bug/error?
In normal terms, if a bug or error is detected in a system, it needs to be communicated to the developer in order to get it fixed.

Right from the first time any bug is detected till the point when the bug is fixed and closed, it is assigned various statuses which are New, Open, Postpone, Pending Retest, Retest, Pending Reject, Reject, Deferred, and Closed.

(Please note that there are various ways to communicate the bug to the developer and track the bug status)

Statuses associated with a bug:
New:
When a bug is found/revealed for the first time, the software tester communicates it to his/her team leader (Test Leader) in order to confirm if that is a valid bug. After getting confirmation from the Test Lead, the software tester logs the bug and the status of ‘New’ is assigned to the bug.

Assigned:
After the bug is reported as ‘New’, it comes to the Development Team. The development team verifies if the bug is valid. If the bug is valid, development leader assigns it to a developer to fix it and a status of ‘Assigned’ is assigned to it.

Open:
Once the developer starts working on the bug, he/she changes the status of the bug to ‘Open’ to indicate that he/she is working on it to find a solution.

Fixed:
Once the developer makes necessary changes in the code and verifies the code, he/she marks the bug as ‘Fixed’ and passes it over to the Development Lead in order to pass it to the Testing team.

Pending Retest:
After the bug is fixed, it is passed back to the testing team to get retested and the status of ‘Pending Retest’ is assigned to it.

Retest:
The testing team leader changes the status of the bug, which is previously marked with ‘Pending Retest’ to ‘Retest’ and assigns it to a tester for retesting.

Closed:
After the bug is assigned a status of ‘Retest’, it is again tested. If the problem is solved, the tester closes it and marks it with ‘Closed’ status.

Reopen:
If after retesting the software for the bug opened, if the system behaves in the same way or same bug arises once again, then the tester reopens the bug and again sends it back to the developer marking its status as ‘Reopen’.

Pending Reject:
If the developers think that a particular behavior of the system, which the tester reports as a bug has to be same and the bug is invalid, in that case, the bug is rejected and marked as ‘Pending Reject’.

Rejected:
If the Testing Leader finds that the system is working according to the specifications
or the bug is invalid as per the explanation from the development, he/she rejects the bug and marks its status as ‘Rejected’.

Postponed:
Sometimes, testing of a particular bug has to be postponed for an indefinite period. This situation may occur because of many reasons, such as unavailability of Test data, unavailability of particular functionality etc. That time, the bug is marked with ‘Postponed’ status.

Deferred:
In some cases a particular bug stands no importance and is needed to be/can be avoided, that time it is marked with ‘Deferred’ status.

Software Testing - How To Log A Bug (Defect)
As we already have discussed importance of Software Testing in any software development project (Just to summarize: Software testing helps in improving quality of software and deliver a cost effective solution which meet customer requirements), it becomes necessary to log a defect in a proper way, track the defect, and keep a log of defects for future reference etc.

As a tester tests an application and if he/she finds any defect, the life cycle of the defect starts and it becomes very important to communicate the defect to the developers in order to get it fixed, keep track of current status of the defect, find out if any such defect (similar defect) was ever found in last attempts of testing etc. For this purpose, previously manually created documents were used, which were circulated to everyone associated with the software project (developers and testers), now a days many Bug Reporting Tools are available, which help in tracking and managing bugs in an effective way.

How to report a bug?
It’s a good practice to take screen shots of execution of every step during software testing. If any test case fails during execution, it needs to be failed in the bug-reporting tool and a bug has to be reported/logged for the same. The tester can choose to first report a bug and then fail the test case in the bug-reporting tool or fail a test case and report a bug. In any case, the Bug ID that is generated for the reported bug should be attached to the test case that is failed.

At the time of reporting a bug, all the mandatory fields from the contents of bug (such as Project, Summary, Description, Status, Detected By, Assigned To, Date Detected, Test Lead, Detected in Version, Closed in Version, Expected Date of Closure, Actual Date of Closure, Severity, Priority and Bug ID etc.) are filled and detailed description of the bug is given along with the expected and actual results. The screen-shots taken at the time of execution of test case are attached to the bug for reference by the developer.

After reporting a bug, a unique Bug ID is generated by the bug-reporting tool, which is then associated with the failed test case. This Bug ID helps in associating the bug with the failed test case.

After the bug is reported, it is assigned a status of ‘New’, which goes on changing as the bug fixing process progresses.

If more than one tester are testing the software application, it becomes a possibility that some other tester might already have reported a bug for the same defect found in the application. In such situation, it becomes very important for the tester to find out if any bug has been reported for similar type of defect. If yes, then the test case has to be blocked with the previously raised bug (in this case, the test case has to be executed once the bug is fixed). And if there is no such bug reported previously, the tester can report a new bug and fail the test case for the newly raised bug.

If no bug-reporting tool is used, then in that case, the test case is written in a tabular manner in a file with four columns containing Test Step No, Test Step Description, Expected Result and Actual Result. The expected and actual results are written for each step and the test case is failed for the step at which the test case fails.

This file containing test case and the screen shots taken are sent to the developers for reference. As the tracking process is not automated, it becomes important keep updated information of the bug that was raised till the time it is closed.

(Please Note: The above given procedure of reporting a bug is general and not based on any particular project. Most of the times, the bug reporting procedures, values used for the various fields used at the time of reporting a bug and bug tracking system etc. may change as par the software testing project and company requirements.)

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