softeare testing concepts

7/31/2019 Softeare Testing Concepts

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SOFTWARE TESTINGCONCEPTS




SOFTWARE TESTING

"Primary role of testing is not

demonstration of correctperformance, but the exposure

of hidden defects."

- G. J. Myers




• It is not sufficient todemonstrate that the software is

doing what it is supposed to do.• It is more important to

demonstrate that the software isnot doing what it is not supposedto do.

SOFTWARE TESTING




TRADITIONAL DEFINITIONS OF TESTING • Establishing confidence that a program does

what it is supposed to do (Hetzel, 1973)

• Confirming that a program performs its

intended functions correctly

• THESE DEFINITIONS ARE

INCOMPLETE AND DESCRIBE ALMOST

THE OPPOSITE OF WHAT TESTING

SHOULD BE!!




WHAT TESTING ACTUALLY IS • Identifying the differences between

expected and actual results

• Process of executing a program (or part of it) with the intention or goal of finding

defects

• Detecting specification errors and

deviations from the specifications.



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ESSENTIALS OF SOFTWARE TESTING • TESTING IS DESTRUCTIVE PROCESS :

A CREATIVE DESTRUCTION

• If a test does not detect a defect actually

present, is it successful or unsuccessful?• Test that detects a defect is valuable

investment: it has helped in improving the

product..




ESSENTIALS OF SOFTWARE TESTING • The quality of the test process

determines the success of testeffort

• The longer the defect remains, themore expensive it is to remove it

• Prevent defect migration by usingearly life cycle testing techniques..




ESSENTIALS OF SOFTWARE TESTING • Use appropriate software

testing tools where required

• Testing is largely a problemof economics

• Exhaustive input testing is

impossible..




ESSENTIALS OF SOFTWARE TESTING • Each test case should provide maximum

yield (probability that the test case will

expose a previously undetected error)

• Investment is measured by the time and

cost to produce, execute and verify test and

communicate

• Investment is limited by schedule and

budget..




ESSENTIALS OF SOFTWARE TESTING • If sole purpose of a test is to validate

specifications were implemented, then:

» testing is an unnecessary and unproductive

activity» testing is designed to compensate for ineffectivesoftware development

• It is risky to develop software and not test it.

• High pressures to deliver software as quicklyas possible: test process must providemaximum value in shortest time..



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Software Testing Concepts

ESSENTIALS OF SOFTWARE TESTING • Testing is no longer:

» after-programming evaluation

» adjunct to the SDLC

• It is:» key integral part of EACH phase of SDLC

• Highest payback comes from detecting

defects early or preventing defects:» avoid incorrect design and coding so as to avoidcorrecting defects later..



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ESSENTIALS OF SOFTWARE TESTING • Aim is to reduce the time ‘wasted’ in defect

removal: concentrate on defect prevention.

• Misconceptions:

» Anyone can test software: no particular skill isrequired!

» Testers can test for quality at the end of aproject!

» Defects found mean blaming the developers.



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PRINCIPLES OF SOFTWARE TESTING

• A programmer should avoid testing his or herown program

• A team should avoid testing its own program

• Thoroughly inspect the results of each test

• Establishing that a program does what it issupposed to do is only half the battle:

»The other, more important half is

seeing whether the program is doingwhat it is not supposed to do..



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• Good testing MUST examine:»users’ requirements

»design objectives

»user interface

»internal structure»AND then execute the code..



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Software Testing ConceptsSICSR MBA IT Sem 3


• Testing is not something done as a formalityat the end of development; it is donethroughout the SDLC to detect defects asearly as possible and prevent defect migrationto subsequent phases

• SOFTWARE TESTING =» Verification (Static Testing)

» +» Validation (Dynamic Testing).



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ESTABLISHING A TESTING POLICY

• Good testing does not justhappen

• It must be planned

• Automation is not the onlyanswer

• Avoid ‘Anti-testing’ messages.

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