Software Engineering Chapter 23 Software Testing Ku-Yaw Chang [email protected] Assistant...

Software EngineeringSoftware Engineering

Chapter 23 Chapter 23 Software TestingSoftware Testing

Ku-Yaw ChangKu-Yaw [email protected]@mail.dyu.edu.tw

Assistant ProfessorAssistant ProfessorDepartment of Computer Science and Information EngineeringDepartment of Computer Science and Information Engineering

Da-Yeh UniversityDa-Yeh University

22Ku-Yaw ChangKu-Yaw Chang Software TestingSoftware Testing

ObjectivesObjectives

Understand the distinctions between validation Understand the distinctions between validation testing and defect testing;testing and defect testing;

Understand the principles of system testing and Understand the principles of system testing and component testing;component testing;

Understand three strategies that may be used to Understand three strategies that may be used to generate system test cases;generate system test cases;

Understand the essential characteristics of Understand the essential characteristics of software tools that support test automationsoftware tools that support test automation


PreamblePreamble

Two distinct goalsTwo distinct goals To demonstrate to the developer and the customer To demonstrate to the developer and the customer

that the software that the software meets its requirementsmeets its requirements..Validation testValidation test

To discover faults or defectsTo discover faults or defects in the software where the in the software where the behavior of the software is incorrect, undesirable or behavior of the software is incorrect, undesirable or does not conform to its specification.does not conform to its specification.

Defect testingDefect testing

Testing can only show the presence of errors, Testing can only show the presence of errors, not their absencenot their absence

– Edsger Dijkstra – Edsger Dijkstra


PreamblePreamble

An abstract view of software testingAn abstract view of software testing Component testingComponent testing

Testing the parts of the systemTesting the parts of the system System testingSystem testing

Testing the system as a wholeTesting the system as a whole

Componenttesting

Systemtesting

Software developer Independent testing team


A Model ofA Model ofthe Software Testing Processingthe Software Testing Processing

Design testcases

Prepare testdata

Run programwith test data

Compare resultsto test cases

Testcases

Testdata

Testresults

Testreports


PreamblePreamble

Exhaustive testing is impossibleExhaustive testing is impossible Every possible program execution sequence Every possible program execution sequence

is testedis tested


ContentsContents

23.1 System testing23.1 System testing

23.2 Component testing23.2 Component testing

23.3 Test case design23.3 Test case design

23.4 Test automation23.4 Test automation


System TestingSystem Testing

Integrate two or more componentsIntegrate two or more components Testing this integrated systemTesting this integrated system

Two distinct phasesTwo distinct phases Integration testingIntegration testing

Access to the source codeAccess to the source codeFind the source of the problemFind the source of the problem

Identify the componentsIdentify the components

Find defects in the systemFind defects in the system Release testingRelease testing

Validating that the system meets its requirementsValidating that the system meets its requirements Black-box testingBlack-box testing

Also called Also called acceptance testingacceptance testing, if customers are involved, if customers are involved


Integration TestingIntegration Testing

A major problem - localizing errorsA major problem - localizing errors Hard to identify where the error occurredHard to identify where the error occurred

An incremental approachAn incremental approach Initially, integrate a minimal system configuration and Initially, integrate a minimal system configuration and

test this systemtest this system Add components and test after each added incrementAdd components and test after each added increment

Regression testingRegression testing Rerun an existing set of testsRerun an existing set of tests


Incremental Integration TestingIncremental Integration Testing

T3

T2

T1

T4

T5

A

B

C

D

T2

T1

T3

T4

A

B

C

T1

T2

T3

A

B

Test sequence 1 Test sequence 2 Test sequence 3


Release TestingRelease Testing

Primary goalPrimary goal Increase the supplier’s confidence that the system Increase the supplier’s confidence that the system

meets its requirementsmeets its requirements

A black-box testingA black-box testing System behavior can be determined by studying its System behavior can be determined by studying its

inputs and related outputsinputs and related outputs Also called functional testingAlso called functional testing


Black-box TestingBlack-box Testing

IeInput test data

OeOutput test results

System

Inputs causinganomalousbehaviour

Outputs which revealthe presence ofdefects


GuidelinesGuidelines

Choose inputs that force the system to generate Choose inputs that force the system to generate all error messagesall error messages

Design inputs that cause input buffers to Design inputs that cause input buffers to overflowoverflow

Repeat the same input or series of inputs Repeat the same input or series of inputs numerous timesnumerous times

Force computation results to be too large or too Force computation results to be too large or too smallsmall


Performance TestingPerformance Testing

Test the system for emergent properties after Test the system for emergent properties after completely integratedcompletely integrated PerformancePerformance ReliabilityReliability

Performance testsPerformance tests Ensure the system can process its intended loadEnsure the system can process its intended load



Construct an operational profileConstruct an operational profile A set of tests that reflect the actual mix of workA set of tests that reflect the actual mix of work

Stress testingStress testing Making demands that are outside the design limits of Making demands that are outside the design limits of

the softwarethe software Be particular relevant to distributed systems based on Be particular relevant to distributed systems based on

a network of processorsa network of processors



Two functions of the stress testingTwo functions of the stress testing It tests the failure behavior of the systemIt tests the failure behavior of the system It stresses the system and may cause defects of It stresses the system and may cause defects of

come to light that would not normally be discovered.come to light that would not normally be discovered.


ContentsContents






Component TestingComponent Testing

The process of testing individual components in The process of testing individual components in the systemthe system Also called Also called unit testingunit testing

GoalGoal To expose faults in these componentsTo expose faults in these components

For most systemsFor most systems Developers are responsible for component testingDevelopers are responsible for component testing


Component TestingComponent Testing

Three types of componentsThree types of components Individual functions or methods within an Individual functions or methods within an

objectobject Object classes that have several attributes Object classes that have several attributes

and methodsand methods Composite components made up of several Composite components made up of several

different objects or functions.different objects or functions.


ContentsContents






Test Case DesignTest Case Design

Design test cases (inputs and predicted outputs) Design test cases (inputs and predicted outputs) to test the systemto test the system System testing System testing Component testingComponent testing

GoalGoal Create a set of test casesCreate a set of test cases

Discover program defectsDiscover program defects

Show that the system meets its requirementsShow that the system meets its requirements


Test Case DesignTest Case Design

Approaches to test case designApproaches to test case design Requirement-based testingRequirement-based testing

Test the system requirementTest the system requirement Mostly at the system-testing stageMostly at the system-testing stage

Partition testingPartition testingIdentify input and output partitionsIdentify input and output partitions

Execute inputs from all partitionsExecute inputs from all partitions Generate outputs in all partitionsGenerate outputs in all partitions

Structured testingStructured testingExercise all parts of the programExercise all parts of the program


Requirement-based TestingRequirement-based Testing

Testing a requirement does not mean just writing Testing a requirement does not mean just writing a single testa single test Normally several tests are requiredNormally several tests are required e.g. The user shall be able to search either all of the e.g. The user shall be able to search either all of the

initial set of databases or select a subset from it.initial set of databases or select a subset from it.One databaseOne database

Two databasesTwo databases

More than two databasesMore than two databases

A validation testA validation test Rather than a defect testingRather than a defect testing


Partition TestingPartition Testing

The input data and output results fall into a The input data and output results fall into a number of different classesnumber of different classes Positive numbersPositive numbers Negative numbersNegative numbers

Each of these classes is an Each of these classes is an equivalence partitionequivalence partition or or domaindomain where the program behaves in an where the program behaves in an equivalent way for each class memberequivalent way for each class member Test cases should be chosen from each partitionTest cases should be chosen from each partition



System

Outputs

Invalid inputs Valid inputs



Identify partitions by using the program Identify partitions by using the program specification or user documentationspecification or user documentation A program accepts 4 to 10 inputs that are five-digit A program accepts 4 to 10 inputs that are five-digit

integers greater than 10,000integers greater than 10,000 A good rule of thumbA good rule of thumb

Boundaries of the partitionsBoundaries of the partitions

Cases close to the mid-point of the partitionCases close to the mid-point of the partition



Between 10000 and 99999Less than 10000 More than 99999

999910000 50000

10000099999

Input values

Between 4 and 10Less than 4 More than 10

34 7

1110

Number of input values


Structural TestingStructural Testing

To exercise all program statementsTo exercise all program statements not all path combinationsnot all path combinations

Test case designTest case design Derived from knowledge of the software’s structure Derived from knowledge of the software’s structure

and implementationand implementation Also called Also called

‘‘white-box’ testingwhite-box’ testing

‘‘glass-box’ testingglass-box’ testing

‘‘clear-box’ testingclear-box’ testing


ContentsContents





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Software Engineering Chapter 23 Software Testing Ku-Yaw Chang [email protected] Assistant...

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