Defect Life Cycle

It indicates the complete life cycle of a defect or a bug right from the stage found, fixed, re-tested and closed.
It consist of various status like open/new, assigned, fixed and close/re-open.

Open - When we got a bug the status is new or open.

Assigned - It will be reported to the concerned person by changing the status to assigned.

Fixed - The developer does the necessary code changes and mark the status as fixed.

Closed/Re-open - Once it is fixed we have to re-test and change the status accordingly i.e, closed if fixed properly or re-open if bug still exists and assign it back to the developer.

Other Status or Flow of the bugs:

Invalid/Rejected

The bug which developer does not accept as a bug and rejected the bug are known as Invalid.

Following are the reasons for invalid bugs:

1. Test engineer has misunderstood the requirement.
   
2. Test engineer referring to old requirement.
   
3. Also it may happen developer has misunderstood requirement.
   

Duplicate

If the same bug is reported more than once it is known as duplicate bug.

Following are the reasons for duplicate bugs:

1. Dependent modules.
   
2. Common features.
   

Not Reproducible

If developer accepts the bug but not able to reproduce or replicate the bug after following the bug report is known as not reproducible.

Following are the reasons for not reproducible bugs:

1.Improper bug report.
2.Data mismatch.
3.Build mismatch.
4.Environment mismatch.
5.Inconsistent.

Can't fixed/Won't fixed

These are the bugs that developers can not solve it due to some constraint or limitations.
Whenever the developer accepts the bug but he is not able to fix the bug as that bug fix may lead to affect whole application is called Can't fixed status.

Following are the reasons for Can't fixed/Won't fixed bugs:

1. Bug is in the core of application.
   
2. No technology support.
   
3. Cost of fixing bug is more than retaining it.
   

Deferred/Postpone

Deferred means postpone in which developer postpone the bug and fixes it in the next release.
Deferred can't be done in the initial stage of a build, it can be done in the last stages of the build.

Following are the reasons for Deferred/Postpone bugs:

1. Due to time constraint.
   
2. Due to impact area.
   

Request for Enhancement

These are the suggestions given by the test engineers towards the enhancement of the software or the application.