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Software Engineering: A Practitioner’s Software Engineering: A Practitioner’s Approach, 6/eApproach, 6/e

Chapter 13a:Chapter 13a:Software Testing StrategiesSoftware Testing Strategies

copyright © 1996, 2001, 2005

R.S. Pressman & Associates, Inc.

For University Use OnlyMay be reproduced ONLY for student use at the university level

when used in conjunction with Software Engineering: A Practitioner's Approach.Any other reproduction or use is expressly prohibited.

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Software Software TestingTesting

Testing is the process of exercising aTesting is the process of exercising aprogram with the specific intent of findingprogram with the specific intent of findingerrors prior to delivery to the end user.errors prior to delivery to the end user.

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What Testing ShowsWhat Testing Shows

errorserrors

requirements conformancerequirements conformance

performanceperformance

an indicationan indicationof qualityof quality

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Who Tests the Who Tests the Software?Software?

developerdeveloper independent testerindependent tester

Understands the system Understands the system

but, will test "gently"but, will test "gently"

and, is driven by "delivery"and, is driven by "delivery"

Must learn about the system,Must learn about the system,but, will attempt to break itbut, will attempt to break itand, is driven by qualityand, is driven by quality

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Testing StrategyTesting Strategy

unit testunit test integrationintegrationtesttest

validationvalidationtesttest

systemsystemtesttest

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Testing StrategyTesting Strategy

We begin by ‘We begin by ‘testing-in-the-small’testing-in-the-small’ and move and move toward ‘toward ‘testing-in-the-large’testing-in-the-large’

For conventional softwareFor conventional software The module (component) is our initial focusThe module (component) is our initial focus Integration of modules followsIntegration of modules follows

For OO softwareFor OO software our focus when “testing in the small” changes from an our focus when “testing in the small” changes from an

individual module (the conventional view) to an OO individual module (the conventional view) to an OO class that encompasses attributes and operations and class that encompasses attributes and operations and implies communication and collaborationimplies communication and collaboration

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Strategic IssuesStrategic Issues

State testing objectives explicitly. State testing objectives explicitly. Understand the users of the software and develop a profile for each user Understand the users of the software and develop a profile for each user

category.category. Develop a testing plan that emphasizes “rapid cycle testing.”Develop a testing plan that emphasizes “rapid cycle testing.” Build “robust” software that is designed to test itselfBuild “robust” software that is designed to test itself Use effective formal technical reviews as a filter prior to testingUse effective formal technical reviews as a filter prior to testing Conduct formal technical reviews to assess the test strategy and test Conduct formal technical reviews to assess the test strategy and test

cases themselves. cases themselves. Develop a continuous improvement approach for the testing process. Develop a continuous improvement approach for the testing process.

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Unit TestingUnit Testing

modulemoduleto beto betestedtested

test casestest cases

resultsresults

softwaresoftwareengineerengineer

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Unit TestingUnit Testing

interface interface local data structureslocal data structures

boundary conditionsboundary conditionsindependent pathsindependent pathserror handling pathserror handling paths

modulemoduleto beto betestedtested

test casestest cases

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Unit Test Unit Test EnvironmentEnvironment

ModuleModule

stubstub stubstub

driverdriver

RESULTSRESULTS

interface interface

local data structureslocal data structures

boundary conditionsboundary conditions

independent pathsindependent paths

error handling pathserror handling paths

test casestest cases

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Integration Testing StrategiesIntegration Testing StrategiesOptions:Options:

•• the “big bang” approachthe “big bang” approach•• an incremental construction strategyan incremental construction strategy

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Top Down IntegrationTop Down Integration

top module is tested with top module is tested with stubsstubs

stubs are replaced one at stubs are replaced one at a time, "depth first"a time, "depth first"

as new modules are integrated, as new modules are integrated, some subset of tests is re-runsome subset of tests is re-run

AA

BB

CC

DD EE

FF GG

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Bottom-Up IntegrationBottom-Up Integration

drivers are replaced one at a drivers are replaced one at a time, "depth first"time, "depth first"

worker modules are grouped into worker modules are grouped into builds and integratedbuilds and integrated

AA

BB

CC

DD EE

FF GG

clustercluster

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Sandwich TestingSandwich Testing

Top modules areTop modules aretested with stubstested with stubs

Worker modules are grouped into Worker modules are grouped into builds and integratedbuilds and integrated

AA

BB

CC

DD EE

FF GG

clustercluster