Topic: Software Bug Life cycle

Bug Life cycle:


In entomology(the study of real, living Bugs), the term life cycle refers to the various stages that an insect assumes over its life. If you think back to your high school biology class, you will remember that the life cycle stages for most insects are the egg, larvae, pupae and adult. It seems appropriate, given that software problems are also called bugs, that a similar life cycle system is used to identify their stages of life. Figure 18.2 shows an example of the simplest, and most optimal, software bug life cycle.

This example shows that when a bug is found by a Software Tester, its logged and assigned to a programmer to be fixed. This state is called open state. Once the programmer fixes the code , he assigns it back to the tester and the bugs enters the resolved state. The tester then performs a regression test to confirm that the bug is indeed fixed and, if it closes it out. The bug then enters its final state, the closed state.

In some situations though, the life cycle gets a bit more complicated.

In this case the life cycle starts out the same with the Tester opening the bug and assigning to the programmer, but the programmer doesn’t fix it. He doesn’t think its bad enough to fix and assigns it to the project manager to decide. The Project Manager agrees with the Programmer and places the Bug in the resolved state as a “wont-fix� bug. The tester disagrees, looks for and finds a more obvious and general case that demonstrates the bug, reopens it, and assigns it to the Programmer to fix. The programmer fixes the bg, resolves it as fixed, and assign it to the Tester. The tester confirms the fix and closes the bug.

You can see that a bug might undergo numerous changes and iterations over its life, sometimes looping back and starting the life all over again. Figure below takes the simple model above and adds to it possible decisions, approvals, and looping that can occur in most projects. Of course every software company and project will have its own system, but this figure is fairly generic and should cover most any bug life cycle that you’ll encounter

The generic life cycle has two additional states and extra connecting lines. The review state is where Project Manager or the committee, sometimes called a change Control Board, decides whether the bug should be fixed. In some projects all bugs go through the review state before they’re assigned to the programmer for fixing. In other projects, this may not occur until near the end of the project, or not at all. Notice that the review state can also go directly to the closed state. This happens if the review decides that the bug shouldn’t be fixed – it could be too minor is really not a problem, or is a testing error. The other is a deferred. The review may determine that the bug should be considered for fixing at sometime in the future, but not for this release of the software.

The additional line from resolved state back to the open state covers the situation where the tester finds that the bug hasn’t been fixed. It gets reopened and the bugs life cycle repeats.

The two dotted lines that loop from the closed and the deferred state back to the open state rarely occur but are important enough to mention. Since a Tester never gives up, its possible that a bug was thought to be fixed, tested and closed could reappear. Such bugs are often called Regressions. It’s possible that a deferred bug could later be proven serious enough to fix immediately. If either of these occurs, the bug is reopened and started through the process again. Most Project teams adopt rules for who can change the state of a bug or assign it to someone else.For example, maybe only the Project Manager can decide to defer a bug or only a tester is permitted to close a bug. What’s important is that once you log a bug, you follow it through its life cycle, don’t lose track of it, and prove the necessary information to drive it to being fixed and closed.

Edited by Sangita - 15May2007 at 11:27pm

Bug Life Cycle & Guidelines

In this tutorial you will learn about Bug Life Cycle & Guidelines, Introduction, Bug Life Cycle, The different states of a bug, Description of Various Stages, Guidelines on deciding the Severity of Bug, A sample guideline for assignment of Priority Levels during the product test phase and Guidelines on writing Bug Description.

Introduction:

Bug can be defined as the abnormal behavior of the software. No software exists without a bug. The elimination of bugs from the software depends upon the efficiency of testing done on the software. A bug is a specific concern about the quality of the Application under Test (AUT).

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.
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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.
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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.
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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.

The test engineer finds the defect send to the dev team with the status as New .
The dev checks the defect is really defect or not if it is defect gives status as Assigned.
if defect is not defect gives status as Reopen
The test eng checks the defect is really rectified or not
The test eng checks the defect is really rectified gives status as close.