Friday, July 24, 2009

Bug Life Cycle:

In software development process, the bug has a life cycle. The bug should go through the life cycle to be closed. A specific life cycle ensures that the process is standardized. The bug attains different states in the life cycle. The life cycle of the bug can be shown diagrammatically as follows: 

The different states of a bug can be summarized as follows:

1. New
2. Open
3. Assign
4. Test
5. Verified
6. Deferred
7. Reopened
8. Duplicate
9. Rejected and
10. Closed

Description of Various Stages:

1. New: When the bug is posted for the first time, its state will be "NEW". This means that the bug is not yet approved.

2. Open: After a tester has posted a bug, the lead of the tester approves that the bug is genuine and he changes the state as "OPEN".

3. Assign: Once the lead changes the state as "OPEN", he assigns the bug to corresponding developer or developer team. The state of the bug now is changed to "ASSIGN".

4. Test: Once the developer fixes the bug, he has to assign the bug to the testing team for next round of testing. Before he releases the software with bug fixed, he changes the state of bug to "TEST". It specifies that the bug has been fixed and is released to testing team.

5. Deferred: The bug, changed to deferred state means the bug is expected to be fixed in next releases. The reasons for changing the bug to this state have many factors. Some of them are priority of the bug may be low, lack of time for the release or the bug may not have major effect on the software.

6. Rejected: If the developer feels that the bug is not genuine, he rejects the bug. Then the state of the bug is changed to "REJECTED".

7. Duplicate: If the bug is repeated twice or the two bugs mention the same concept of the bug, then one bug status is changed to "DUPLICATE".

8. Verified: Once the bug is fixed and the status is changed to "TEST", the tester tests the bug. If the bug is not present in the software, he approves that the bug is fixed and changes the status to "VERIFIED".

9. Reopened: If the bug still exists even after the bug is fixed by the developer, the tester changes the status to "REOPENED". The bug traverses the life cycle once again.

10. Closed: Once the bug is fixed, it is tested by the tester. If the tester feels that the bug no longer exists in the software, he changes the status of the bug to "CLOSED". This state means that the bug is fixed, tested and approved.

While defect prevention is much more effective and efficient in reducing the number of defects, most organization conducts defect discovery and removal. Discovering and removing defects is an expensive and inefficient process. It is much more efficient for an organization to conduct activities that prevent defects.

Guidelines on deciding the Severity of Bug:

Indicate the impact each defect has on testing efforts or users and administrators of the application under test. This information is used by developers and management as the basis for assigning priority of work on defects.

A sample guideline for assignment of Priority Levels during the product test phase includes:

1.      Critical / Show Stopper — An item that prevents further testing of the product or function under test can be classified as Critical Bug. No workaround is possible for such bugs. Examples of this include a missing menu option or security permission required to access a function under test.

2.      Major / High — A defect that does not function as expected/designed or cause other functionality to fail to meet requirements can be classified as Major Bug. The workaround can be provided for such bugs. Examples of this include inaccurate calculations; the wrong field being updated, etc.

3.      Average / Medium — The defects which do not conform to standards and conventions can be classified as Medium Bugs. Easy workarounds exists to achieve functionality objectives. Examples include matching visual and text links which lead to different end points.

4.      Minor / Low — Cosmetic defects which does not affect the functionality of the system can be classified as Minor Bugs.

Guidelines on writing Bug Description:

Bug can be expressed as "Result followed by the action". That means, the unexpected behavior occurring when a particular action takes place can be given as bug description.

1.      Be specific. State the expected behavior which did not occur – such as after pop-up did not appear and the behavior which occurred instead.

2.      Use present tense.

3.      Don't use unnecessary words.

4.      Don't add exclamation points. End sentences with a period.

5.      DON'T USE ALL CAPS. Format words in upper and lower case (mixed case).

6.      Mention steps to reproduce the bug compulsorily.




Tuesday, July 7, 2009


As software dominates most discussions in the information technology business, one need to examine carefully where we are headed in software reliability. It is reasonable to ask about the nature of software faults and the remedy for them, either from a fault-tolerance perspective or, more generally, on a software dependability front. There are conferences on this topic and over 300 technical papers that discuss some of its aspects. However, as many industry specialists agree, software is one area in the information technology industry which continues to baffle the scientist from a dependability perspective. While hardware & technology have seen four orders of magnitude improvement in the past decade, software has probably marginally improved or, some will argue, gotten worse. One then wonders if research in this area is headed in the right directions.

Thus, it is vital to examine some of the fundamentals, e.g., "What is a software failure?" This question is usually assumed to be well understood. However, when one examines it closely, it is startling how little is truly understood regarding those faults that matter. This problem is appreciably better understood in hardware systems, or systems, have been better tracked over the years and there is a larger body of experience in failure modes & effects analysis. However, the counterpart in software is far less understood. It is further complicated by a lack of clarity as to what is a software failure.

Ram Chillarege
IEEE Transactions on Reliability, Vol. 45, No. 3, September, 1996.