Fundamentals Of Testing

Question 1

Why testing is important

Answer 1

-costly if mistakes weren’t found
-7/10 it projects fail - can be because for poor testing
-testing can represent 40% of costs
-cost,time and quality benefits to software testing

Question 2

Why is testing under time pressure

Answer 2

As it’s normal one of the last tasks prior to customer delivery, appropriately planned tests are often subject to time pressure

Question 3

Example of failure in software

Answer 3

Nasa Nara lander, crashed due to a fault, cost over 50mil 1999

Question 4

Why does testing matter

Answer 4

Inadequate testing costs us 22-59 billion annually
Can cost lives - therac-25 radiation machine 3 dead
Testing shows if our programs are reliable

Question 5

How is smaller scale testing done

Answer 5

Reported by users and clients. Issues prioritised examined and resolved . Some issues result of defects

Question 6

Causes of software defects

Answer 6

Human error e.g. in code or system (bug or defect)
Environmental conditions e.g. radiation, pollution can cause faults in firmware
Developer error -> software defect -> software fails

Question 7

A failure is present…

Answer 7

A failure is present if a user expectation is not fulfilled adequately
E.g. products too hard to use, too slow

Question 8

What is a failure

Answer 8

Deviation of the software from its expected delivery or surface
Happens when software does the wrong thing

Question 9

What can a failure also be called

Answer 9

Problem, incident, issue

Question 10

What is a defect

Answer 10

A manifestation of human error in software
- can be caused by requirements, design or coding errors

Question 11

How can defects be discovered

Answer 11

Inspecting code or from software failures

Question 12

What can a defect also be called

Answer 12

Bug or fault

Question 13

What is an error

Answer 13

Human action producing an incorrect result
When humans make errors they introduce faults to program code

Question 14

An error is not

Answer 14

Just an accident or mistake
Not necessarily just incompetence

Question 15

Are errors inevitable

Answer 15

Errors are inevitable in a complex activity

Question 16

Why is testing important

Answer 16

Reducing risk of problems in operatioanl environment
Contributes to quality
Contractual or legal requirements
Testing provides evidence it complies to standards

Question 17

Why is complete testing not feasible

Answer 17

Domain of possible inputs too large
Design issues may be too complex to test

Question 18

Where are bugs normally found

Answer 18

In clusters
Bug fixing and maintenance are error prone and may cause unintended faults

Question 19

What is testing

Answer 19

Exploration of a system to find defect
Repeated to ensure defect corrections have been effective

Question 20

What is debugging

Answer 20

Developers identify cause of defects in code and undertake corrections
Debugging is done before testing
Can be used to understand root cause of failures

Question 21

Name some test objectives

Answer 21

Finding defects
Gaining confidence about level of quality
Preventing defects

Question 22

What is static testing

Answer 22

Testing without executing the program
E.g. software inspections

Question 23

What is dynamic testing

Answer 23

Testing by executing program with real inputs

Question 24

What is maintenance/regression testing

Answer 24

Testing that no new errors have been introduced

Question 25

Unit testing

Answer 25

Addresses quality of individual units

Question 26

Integration testing

Answer 26

Checks if individual components operate together

Question 27

System testing

Answer 27

Checks if system delivers desired functionality

Question 28

Testing vs debugging

Answer 28

Testing shows failures caused by defects
Debugging identifies cause if defect and repairs code and makes sure it’s fixed