Testing and Testing and Evaluating Evaluating

Software Design and Development Software Design and Development Chapter 6 summaryChapter 6 summary

ContentsContentsTesting the SoftwareTesting the Software Comparison of the Solution with the original Design Comparison of the Solution with the original Design

SpecificationSpecification Generating relevant Test Data for Complex SolutionsGenerating relevant Test Data for Complex Solutions Levels of TestingLevels of Testing Live Test DataLive Test Data BenchmarkingBenchmarking Quality AssuranceQuality Assurance

Reporting on the Testing ProcessReporting on the Testing Process DocumentationDocumentation CommunicationCommunication

Testing the Software SolutionTesting the Software Solution

Testing is carried out to find errorsTesting is carried out to find errors

Software developers must continually ensure that the original specifications Software developers must continually ensure that the original specifications

are being met in the software product being developedare being met in the software product being developed

Construction of appropriate test data and adequate testing prevents the Construction of appropriate test data and adequate testing prevents the

occurrence of major problems in the finished program that are expensive to occurrence of major problems in the finished program that are expensive to

fix.fix.

Test data must be sufficient to ensure the program is completely operational Test data must be sufficient to ensure the program is completely operational

and free of logic errors. and free of logic errors.

Test data must be constructed to test every part of a program, including the Test data must be constructed to test every part of a program, including the

mainline of the program and any modules used by the program. mainline of the program and any modules used by the program.

What should be tested?What should be tested?Test data should testTest data should test

All parts of the programAll parts of the program

Each path of execution - test data should be sufficient to test the Each path of execution - test data should be sufficient to test the

termination and correct exit of each loop. To test each path in nested If termination and correct exit of each loop. To test each path in nested If

statement / CASE structure. statement / CASE structure.

Boundary conditions - the values of variables or expressions that Boundary conditions - the values of variables or expressions that

determine the choice of available options to be taken. exampledetermine the choice of available options to be taken. example

At the very minimum to execution paths should always be tested rather than At the very minimum to execution paths should always be tested rather than

boundary conditions. Large programs should be tested using other testing boundary conditions. Large programs should be tested using other testing

mechanisms.mechanisms.

Testing should include :Unit testing, program testing and system testing Testing should include :Unit testing, program testing and system testing

Unit or Module TestingUnit or Module TestingStructured programming results in modules, each of which can be tested individuallyStructured programming results in modules, each of which can be tested individually

Subprograms can be tested as a black box where data is entered and results are shown.Subprograms can be tested as a black box where data is entered and results are shown.

In In black box testingblack box testing, only the inputs and outputs are checked. The processes that achieve these , only the inputs and outputs are checked. The processes that achieve these results are ignored.results are ignored.

Subprograms can also be tested as a white box where the algorithm of the subprogram is Subprograms can also be tested as a white box where the algorithm of the subprogram is understood and each path of execution can be tested appropriately.understood and each path of execution can be tested appropriately.

White box testingWhite box testing examines all the data paths in a module. examines all the data paths in a module.

A driver program may be developed to test modules in a program. The driver substitutes for the A driver program may be developed to test modules in a program. The driver substitutes for the main program, calling the subprogram and supplying the necessary values for any variables. main program, calling the subprogram and supplying the necessary values for any variables.

A driver is a temporary section of code that is created to test an individual procedure or module by A driver is a temporary section of code that is created to test an individual procedure or module by calling it up and executing it.calling it up and executing it.

Program TestingProgram TestingIt is a minimum requirement that the test data tests each logical pathway and program It is a minimum requirement that the test data tests each logical pathway and program

branch that can be entered. branch that can be entered.

All modules are called and executed at least once or when expectedAll modules are called and executed at least once or when expected

This way, the entire program can be completely tested.This way, the entire program can be completely tested.

Screen elements such as menus and buttons must be tested to ensure they are Screen elements such as menus and buttons must be tested to ensure they are

functioning correctly.functioning correctly.

System TestingSystem Testing

During system testing, the program is tested in a variety of operating environments.During system testing, the program is tested in a variety of operating environments.

The software may function in the development system or a controlled environment The software may function in the development system or a controlled environment

however, when implemented on the users computer, problems may arise.however, when implemented on the users computer, problems may arise.

The effect of hardware, operating systems and other software may create errors that The effect of hardware, operating systems and other software may create errors that

have not been previously detected.have not been previously detected.

System testing is carried out to detect errors at the software / hardware interface,System testing is carried out to detect errors at the software / hardware interface,

Carried out by users rather than developers. System tests treat the program as a black Carried out by users rather than developers. System tests treat the program as a black

box.box.

Live Test DataLive Test DataLive data is real data, used to ensure that a program works under real-life Live data is real data, used to ensure that a program works under real-life

conditions.conditions.

Real data is supplied by the client or can be generated by CASE tools.Real data is supplied by the client or can be generated by CASE tools.

Stress testing involves increasing the load on a program in an attempt to make it fail.Stress testing involves increasing the load on a program in an attempt to make it fail.

Live Test Data should include:Live Test Data should include:

Larger File SizesLarger File Sizes

Mix of Transaction TypesMix of Transaction Types

Response TimesResponse Times

Volume dataVolume data

Interfaces between ModulesInterfaces between Modules

Comparison with Program Test DataComparison with Program Test Data

Live dataLive data is used to ensure that the system response times are appropriate. Response times are dependent on all the system components, together with their interactions with each other and other processes that may be occurring concurrently. Response times should be tested on minimum hardware using typical data of different types.

Interface tests Interface tests will ensure that the correct numbers of parameters are sent to and from the module and that the format is correct. Interface tests will also detect conflicts between local and global variables.

A variety of different transaction types and sequences of data entry should be tested with live data. Module and program testing usually involve testing specific transactions or processes one at a time. During system testing, transactions occur in random order and checked to see if any errors arise

Software developers generate test data to test the limits of the system that may not be tested under normal use. (to ensure the system has scalability)

A program developed to access files should be tested with a range of file types and sizes. The use of large files will highlight problems associated with data access.

BenchmarkingBenchmarkingA benchmark is a standard against which performance of a computer program can be

assessed against expected outcomes and other similar products on the market.

Established programs are often used as a benchmark to indicate the quality and

performance expectations of a new product.

Benchmarks allow users of software products to make informed purchasing decisions

Quality AssuranceQuality AssuranceQuality Assurance is a set of procedures used to certify that a generated product meets specified Quality Assurance is a set of procedures used to certify that a generated product meets specified

criteria with respect to quality and reliability.criteria with respect to quality and reliability.

CCorrectness - Does it do what it is supposed to do?orrectness - Does it do what it is supposed to do?

RReliability - Does it do it all of the time?eliability - Does it do it all of the time?

EEfficiency - Does it do it the best way possible?fficiency - Does it do it the best way possible?

IIntegrity - Is it secure?ntegrity - Is it secure?

MMaintainability - Can it be understood?aintainability - Can it be understood?

(CREIM)(CREIM)

Quality Assurance is not just about testing a product once it has been completed. Its about Quality Assurance is not just about testing a product once it has been completed. Its about

periodically performing inspections, reviews and tests on the system being developed. periodically performing inspections, reviews and tests on the system being developed.

Quality assurance techniques should be implemented throughout the software development Quality assurance techniques should be implemented throughout the software development

process.process.

Alpha & Beta TestingAlpha & Beta TestingAlpha TestingAlpha Testing

Testing of the final solution by personnel within the software Testing of the final solution by personnel within the software

development company prior to the product’s release.development company prior to the product’s release.

The client uses the system in a controlled environment and checks to see The client uses the system in a controlled environment and checks to see

if it meets their requirements.if it meets their requirements.

Beta Testing(Acceptance Testing)Beta Testing(Acceptance Testing)

Testing of the final solution by a limited number of users outside the Testing of the final solution by a limited number of users outside the

software development company using real world data and conditions.software development company using real world data and conditions.

The program is given to a number of potential clients who will also report The program is given to a number of potential clients who will also report

to the developers any problems they encounter in the program.to the developers any problems they encounter in the program.

Reporting on the Testing ProcessReporting on the Testing ProcessRequired DocumentationRequired Documentation A test data table should be created to show the test data to be used A test data table should be created to show the test data to be used

and the reason why this item of test data was selected.and the reason why this item of test data was selected. Test requirements - What needs to be tested?Test requirements - What needs to be tested? Test plan - How do we implement these tests?Test plan - How do we implement these tests? Test data and expected results - What are the necessary inputs and Test data and expected results - What are the necessary inputs and

the expected outputs?the expected outputs? Test results - Do the actual results match the expected results?Test results - Do the actual results match the expected results? Recommendations - What needs to be done nowRecommendations - What needs to be done now

A desk-check table is used to document the test data A desk-check table is used to document the test data used and compare the expected output with the actual used and compare the expected output with the actual output of the algorithm or program.output of the algorithm or program.

CASE Tools that aid in the testing process:CASE Tools that aid in the testing process: Tools to generate or acquire data to be used during Tools to generate or acquire data to be used during

testingtesting Tools that analyse the source codeTools that analyse the source code Simulation tools to mimic the roles of hardware or Simulation tools to mimic the roles of hardware or

other software that interacts with the programother software that interacts with the program

CommunicationCommunicationIndependent testers are less likely to approach the program with Independent testers are less likely to approach the program with

preconceptions.preconceptions.

It is essential that the user is provided with the opportunity to evaluate the It is essential that the user is provided with the opportunity to evaluate the

solution that has been developed.solution that has been developed.

Results of the testing provides an opportunity for the users to evaluate and Results of the testing provides an opportunity for the users to evaluate and

discuss the functionality of the new system.discuss the functionality of the new system.

Alpha and Beta testing help to provide users with the opportunity to use the Alpha and Beta testing help to provide users with the opportunity to use the

program.program.

After the customer has approved a program, it can be released to the general After the customer has approved a program, it can be released to the general

market.market.

The EndThe End

Boundary ConditionsBoundary ConditionsCASEWHERE age is CASEWHERE age is

<=3: output “Too young for school”<=3: output “Too young for school”<=18: output “Could be at school”<=18: output “Could be at school”OTHERWISE: output “Too old for school”OTHERWISE: output “Too old for school”

ENDCASEENDCASE

An appropriate set of data could therefore be An appropriate set of data could therefore be

22 3 3 18 18 20. 20.

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Black box TestingBlack box Testing

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White box TestingWhite box Testing

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