Fundamentals of testing

We need to understand, explain, give reasons, compare, classify, categorize, give examples and summarize;

Terms we need to understand in this Chapter are

1. Bug
2. Defect
3. Error
4. Failure
5. Fault
6. Mistake
7. Quality
8. Risk.

Error:

·Mistake made by the human beings

·An error or defect in software or Hardware that causes a program to malfunction

Defect :

* Due to mistake it produces a fault or bug in the code software or a system, or in a document.
* A defect is any variance between actual and expected results.

Failure :

* If a defect in code is executed, the system will fail to do
* what it should do or do something it shouldn’t

So the relation is

Error =>Defect=>Failure

Defect :

* Problem in algorithm leads to failure
* Non conformance to requirements or functional / program specification

Bug:

* Deviation from the expected result.
* It is a fault in a program which causes the program to perform in an unintended or unanticipated manner

Causes for Defects:

Defects occur because human beings are fallible and because there is

* time pressure,
* complex code,
* complexity of infrastructure,
* changed technologies, and/or many system interactions.

Causes for Failures

Failures can be caused by

* environmental conditions as well: radiation, magnetism, electronic fields,
* pollution can cause faults in firmware or influence the execution of software by changing
* hardware conditions.

Purpose of testing :

* Reduce the risk
* Contribute to the quality of the software system
* Could give confidence in the quality of the software if it finds few or no defects

Quality assurance :

Lesson Learnt from the previous projects and by understanding the root cause of defects found in other projects, processes can be improved, which in turn should prevent those defects from

Reoccurring and, as a consequence, improve the quality of future systems.

What is Risk?

Uncertainty — An event may occur or may not occur

Why is Risk arises?

• Uncertainty

• Inexperience

• Inability to accurately forecast

How much testing is enough?

* Level of risk, including technical and business product and project risks,

* Project constraints such as time and budget