Defect, Error, Failure, Fault Tanımları

Defect - Kusur
Açıklaması şöyle.

An aspect of a software system that may cause the system to depart from its intended behaviour. A defect is the potential for a fault.
If the defect is downstream from the design phase, then it will represent a design violation, and may be policed using contract programming enforcements.

Error - Yanlış
Açıklaması şöyle. İnsan tarafından yapılan yanlış anlamına gelir

A wrong decision made during the development of a software system.

Error'a sebep olan şeylerle ilgili bir açıklama şöyle.

In my experience bugs are a consequence of (in no particular order):

1. Poorly defined or constantly changing requirements.
2. Too much work for the amount of time provided, which leads to rushing, which leads to mistakes, and insufficient time to test and fix defects before release.
3. Lack of peer code reviews (may be related to point 2).
4. Insufficient QA resourcing or lack of automated testing to efficiently and effectively test for regressions.
5. Poor morale amongst the development/QA team (probably caused by the above points).

As per the Lean methodology, ~94% of defects are caused by poor processes. Only 6% are caused by individuals.

Fault - Hata
Açıklaması şöyle. Hatanın yazılımda gerçekleşmesi.

The event of a software system behaving in conflict with its design. A fault is the reification of a defect.

Hatanın tek sebebi insan yanlışı değildiri. Eskime, yıpranma gibi sebepler de hataya sebep olabilir.

Failure
Açıklaması şöyle. Başarısızlık. Fault sonucunda oluşur.

The condition whereby a software system does not provide the functionality prescribed by its specification.Failures may be caused by failure in design or in coding.