In terms of software testing, bugs indicate something goes wrong violating the initial intention. There are three terms with shared meaning of ‘bug’: error, defect, and failure. However, these terms are not the same and can not interchange each other. So, what is the difference?
Defect vs Failure vs Error
Errors are software mistakes triggered either by internal (software breaches) or external factors (users’ mistakes / improper use of software). Internal impacts also include viruses or any other malicious software.
The error detected after the software release is considered to be a defect . It highlights wrong implementation of software functionality. When under specific conditions, a software defect appears, the wrong result will be produced. This causes a failure - breach occurs after successful software launch.
It is important to note that not all the defects will result in a failure. There are many ones that remain inactive and cannot actually be discovered.
Failures may appear because of the following reasons:
- Software execution might be changed or prevented because of various faults, like firmware faults, hardware faults, electronic pollution, being faced with a magnetic field and even radiation bursts.
- Human error can cause failures when software interaction is improper, like when an input is improper or an output ends up misinterpreted.
- Failure can also appear when someone is deliberately causing them which is often included in a test plan checklist to simulate user behavior that could lead to system failure.
Some Things on Software Failure to Be Aware of
- During software testing, it is possible to observe behavior differences for functionalities or features. This is not necessarily because of failures. It is possible because of wrong test data, improper test environment, etc. Incidents are reported because of this, commonly referred to as incident reports. The situation or condition that has to be further analyzed is labeled as being an incident. Dealing with incidents leads to figuring out whether what happened was a failure or not.
- Bugs or defects are not always introduced due to the users’ actions. A defect or a bug can also be put in by the business analyst. For instance, a defect may appear because of incomplete requirement specification provided to the development team.
- Bugs or defects are reported to evaluate the quality of software product. In order to earn the customers / users’ trust, products should be of a high quality as well as they should be delivered in time. This can only happen when defects and situations that lead to failure are minimized. There are always errors that can appear but software testing aims to minimize their number and severity.