Chap 1- Introduction to Software Testing

8/3/2019 Chap 1- Introduction to Software Testing

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BITP 3213Software Testing & Quality Assurance

byMadam Nor Haslinda Hj Ismail

Email:[email protected]

Phone: 331 6521Room: Ground Floor FTMKbuilding

Semester 1, 2010/2011 Fakulti Teknologi Maklumat dan Komunikasi
mailto:[email protected]:[email protected]


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Fakulti Teknologi Maklumat dan Komunikasi

Week 1

Introduction to Software Testing


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Human Error Fault Failure

can lead to can lead to


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Overview

What is Software Testing? Objectives of Software Testing

General Failure Terminology

Impact of Software Error

Real-life cases Critical Choice in Software Testing

Fundamental of Software Process

Type of Software Testing

Testing and Quality

Career in Software Testing



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Software Testing OverviewStudies have observed that the cost of correcting

software bugs has tremendously increased thetotal cost of a software project.

Defect. Fault. Problem. Error. Incident.Variance. Failure. Inconsistency

It is crucial to detect the bugs at an early stage.

Software Testing



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When to consider that a softwarehas Bugs?

(The 5 rules)1. The software doesnt do something that the product

specification says.

2. The software does something that the product specification says

it shouldnt do.3. The software does something that the product specification

doesnt mention

4. The software doesnt do that the product specification doesntmention but should

5. The software is difficult to understand, hard to use, or-anything which a tester think that will be viewed as not right bythe end user.



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The 5 Rules : Rule 1

The software doesnt do something that the

product specification says.

Example :-

The + key of a calculator should do the addition.But it doesnt do any calculation or instead it

works as subtraction.



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The software does something that the productspecification says it shouldnt do.

Example:-

The product specification specifies that thecalculator should never crash, lock up or

freeze. Yet, when you press Enter key, itstops responding to any of your next input.



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The software does something that the productspecification doesnt mention

Example:-It is specified that the calculator should only do

addition, subtraction, multiplication and division.Nevertheless, there is an additional of a squareroot function, which being added by programmerbecause he/she things the function is nice tohave.



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The software doesnt do that the product

specification doesnt mention but should

Example:-

The calculation of a calculator is wrongly calculatedif the battery is weak. This may not be specifiedin the specification.



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The software is difficult to understand, hard touse, or- anything which a tester think that willbe viewed as not right by the end user.

Example:-

As a tester, you will be the first person to use thesoftware product. Thus, if the tester feels thereis something not right for whatever reason, thenits consider as a bug.



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Why bugs occur in SoftwareDevelopment?

Missing requirements or therequirements/specifications are not welldocumented. e.g. Contradiction, ambiguity,incomplete requirement

Volatile requirementsThe requirements areconstantly changing.

Communication problem among team members.

No team work



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What is Software Testing?Definition

Process of exercising software to confirm that itsatisfies requirements and identify differences

between expected and actualresults(Khanapi, 2004)

Testing is the process of executing a programwith intention of finding errors

(Myers, 1979)



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Definition

The measurement of software quality

(Hetzel, 1983)

The process of operating a system or component

under specified conditions, observing or

recording the results, and making an evaluationof some aspect of the system or component

(IEEE, 1990)



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Definition : Summary

Software testing is a process by which people,

methods, measurements, tools and equipmentare integrated to test a software product.



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Process A quality process and planning determines the

success of the test effort

People Software testing is a professional discipline , thus

need trained and skilled people with the right andpositive attitudes.

Methods

There are different methods and techniques to beapplied in testing. E.g White-box, black box,



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Measurements

- Used to calculate the quality of a softwareproduct.

Tools and Equipments

- A wide variety of tools to make the testing moreefficient and faster.

- E.g. Using automated tool to re-run the test for

a modified software product. Save time and ableto test thoroughly.



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Basic forms of Testing

VerificationAre we building the product right?

Is the process of evaluating a system orcomponent to determine whether the products of

a given development phase satisfy the conditionimposed at the start of the phase.

ValidationAre we building the right product

Is the process of evaluating a system or

component during or at the end of thedevelopment process to determine whether itsatisfied specified requirements.



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Objectives of Software Testing

To identify and reveal as many errorsas possiblein the tested software

To produce a quality software product, which the

software can be used, and used successfully To bring the tested software, after correction of

the identified errors and retesting, to anacceptable level of quality



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Objectives of Software Testing

To perform the required tests efficiently andeffectively, within budgetary and schedulinglimitations

To compile a record of software errors for use inerror prevention



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General Failure Terminology

Error :

An incorrect implementation of a program

Fault :

An incorrect or unexpected behavior of a programin response to a real-world condition resulting fromerrors

Failure : Occurs when a program is prevented from

achieving its mission resulting from faults



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Relationship : Error-Fault-Failure

Error made by a person.- Avoidable through training,process improvement, or similar

Leading to a fault in the program

- Detectable in review

Causing a noticeable failure inthe system

- Detectable trough testing



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Impact of software error

Case 1

The first Venus probe missed its target in 1979

because a full stop(.) was used in place ofcomma(,) in a Fotran program.

The company lost several hundred million dollarsworth of effort.



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Case 2

In 1984, the southern French Tarn Valley was

flooded due to the failure of an automatic locksystem at Requista where it couldnt recognize

the faulty flood message.

A massive flood which caused catastrophic.



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Case 3

Years before year 2000, most systems were using

the 2-digit date format. (E.g. 1973 as 73). Whenit hits year 2000, problems occurred when thesystems recognized the 00 as year 1900 insteadof 2000.

Estimated that several hundred billions were spent,worldwide to correct the date format.



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Critical choices in SoftwareTesting

What, when and how to test?What to test?

Test the right things! ensure the most critical

things are tested and not waste limited testingresources on less important items.

When to test?

Test early! focus on detecting the error closer tothe phase where it introduce. E.g. V modelTesting



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How to test?

Test effectively and cost-effectively! Identifythe critical/important area to be tested byconsidering the worthwhile from financialpoint of view.

The more effective the error detection, the greaterthe savings in development and maintenance costsover the life of the product. Several exampleshave indicated that partial testing can yield saving

of 1.5 times its cost; full testing can yields savingsup to 2 times its cost

(Lewis, 1992: p.280)


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RISKS and Prioritization

To determine : What to test first?

What to test most?

How thoroughly to test each item?

Example of general risks to be considered : risk of missing important faults

risk of incurring failure costs

risk of releasing untested or under-tested software

risk of losing credibility and market share risk of missing a market window

risk of over-testing, ineffective testing



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Fundamental of Test Process

Test planning and control

Test analysis and test design

Test implementation and test execution

Test evaluation of the test exit criteria

Post testing activities : Review



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Types of Software Testing

Unit Testing Test particular function or codemodule : micro level testing

Integration Testing Test the integrated/combined

components of code modules, individualapplication, client and server application andetc.

Performance Testing Test the performance of a

software productSystem Testing Test the system as a whole.



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Regression Testing Is used to check that thechanges made to the program have notintroduce any new faults in the system

User Acceptance Testing Test the final endproduct by a group of end users to determine thesatisfaction of the customers

Usability TestingUsed to test user-friendliness

of the software product



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What makes a good Tester?

They are explorers As a tester, you are notbound to only one specific application/product.You must not afraid to venture into unknownsituations.

They are troubleshooters You must be able tofigure out the reason why something is not

working.



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They are relentless Persistence and a strongsense of mission to systematically locate theweaknesses in a complex structure anddemonstrates it failures. There are bugs that

quickly vanish or difficult to re-create. Ratherthan dismiss it as fluke, they will try everypossible way to find it.

They are creative Imaginative. Able to come outwith different possibleways/scenarios/approaches in finding the bugs.



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They exercise good judgment - A tester need tomake fine decision about what they will test, howlong will it take, and whether the problem theyre

looking at is really a bug.

They are tactful and diplomatic A tester is alwaysa bearers of bad news. He/she has to conveythe bugs to appropriate party. This must be

done in professional and diplomatic manner sothat, the other party will not feel offended orpersonally being attacked. A team player

attitude.Fakulti Teknologi Maklumat dan Komunikasi


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Testing and Quality

Testing measures the quality of software product.

Testing can find faults; when they are removed,

software quality (and possibly reliability) isimproved.



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Career in Software Testing


Why choose careerin Software Testing?

Increase

productivity

Wide range ofcareer option

Career Path/Options

Test Engineer Test > Test

Manager

QA Lead QAManager

Option byspecialized intesting tool

Key areas to moveahead

Domain

knowledge

ToolsKnowledgeAutomatedTesting

CertificationsE.g. ISTQB,QAI, ASQ


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Find the solution! How much more does it cost to fix a bug

found after the product is released that itdoes from the very start of the project?

Give three reason why the productspecification is usually the largest source ofbugs in a software product

Find 2 article from ACM & IEEE Journal

regarding Software Testing from Year 2009until 2011.



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Next Chapter

Week 2: Software Testing & SDLC


Documents

Chap 1- Introduction to Software Testing