softeare testing concepts
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7/31/2019 Softeare Testing Concepts
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SOFTWARE TESTINGCONCEPTS
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SOFTWARE TESTING
"Primary role of testing is not
demonstration of correctperformance, but the exposure
of hidden defects."
- G. J. Myers
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• 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
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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!!
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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..
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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..
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ESSENTIALS OF SOFTWARE TESTING • Use appropriate software
testing tools where required
• Testing is largely a problemof economics
• Exhaustive input testing is
impossible..
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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..
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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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Software Testing Concepts
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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Software Testing Concepts
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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Software Testing Concepts
PRINCIPLES OF SOFTWARE TESTING
• 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
PRINCIPLES OF SOFTWARE TESTING
• 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).