WIXLIB

What is Software QualityAssurance?When we talk about software quality, we are actuallytalking about the evaluation of the software basedon certain attributes. A software quality is definedbased on the study of external and internal featuresof the software. The external quality is defined basedon how software performs in real time scenario inoperational mode and how useful it is for its users.The internal quality on the other hand focuses onthe intrinsic aspects that are dependent on thequality of the code written. The user focuses moreon how the software works at the external level, butthe quality at external level can be maintained only ifthe coder has written a meaningful good qualitycode.What Is Software Quality Assurance?Presently there are two important approaches thatare used to determine the quality of the software:1 Defect Management Approach2 Quality Attributes approachSoftware QualityAs mentioned before anything that is not in line withthe requirement of the client can be considered as adefect. Many times the development team fails tofully understand the requirement of the client whicheventually leads to design error. Besides that, theerror can be caused due to poor functional logic,wrong coding or improper data handling. In order tokeep a track of defect a defect managementapproach can be applied. In defect management,categories of defects are defined based on severity.The number of defects is counted and actions aretaken as per the severity defined. Control charts canbe created to measure the development processcapability.12

Defect Management ApproachQuality Attributes ApproachQuality Attribute Approach on the other handfocuses on six quality characteristics that are listedbelow:1. Functionality: refers to complete set of importantfunctions that are provided by the software Suitability: whether the functions of thesoftware are appropriate Accurateness: are the functions implementedcorrectly? Interoperability: how does the softwareinteract with other components of the system? Compliance: is the software in compliance withthe necessary laws and guidelines?Security: Is the software able to handle datarelated transaction securely?2. Reliability: this refers to the capability of softwareto perform under certain conditions for a definedduration. This also defines the ability of the systemto withstand component failure. Maturity: Frequency of failure of software13

Recoverability: this gives an idea of a system’sability to get back into full operation afterfailure.3. Usability: refers to the ease of use of a function. Understandability: how easily the functions canbe understood Learn ability: How much effort the users ofdifferent level need to put in to understand thefunctions.4. Efficiency: generally depends on good architecture and coding practices followed while developingsoftware.5. Maintainability: also known as supportability. It isgreatly dependant on code readability andcomplexity and refers to the ability to identify and fixa fault in a software: Analyzability: identification of the main causeof failure. Changeability: defines the effort that goes inmodification of code to remove a fault. Stability: how stable a system is in itsperformance when there are changes made toit Testability: how much effort goes in testing thesystem.6. Portability: Ability of the system to adopt tochanges in its environment Adaptability: how easily a system adapts to thechanges made in specifications Installability: how easily a system can beinstalled. Conformance: this is same as compliance infunctionality. Replaceability: how easy it is to replace acomponent of the system in a given environment.Cost of Software QualityCost of quality is important because when youdecide to conduct software testing for your productyou are actually going to invest your time, moneyand effort in getting quality checks done. Byconducting an analysis of cost of software qualityyou would know what the return on that investment(ROI) is.14

Cost of Software QualityCost of quality is calculated by analyzing theconformance costs and non conformance costs. Aconformance cost is related to:12Prevention costs: amount spent on ensuringthat all quality assurance practices are followedcorrectly. This includes tasks like training theteam, code reviews and any other QA relatedactivity etc.Appraisal costs: this is the amount of moneyspent on planning all the test activities andthen carrying them out such as developing testcases and then executing them.The non conformance cost on the other hand is theexpense that arises due to:1 Internal failures: it is the expense that ariseswhen test cases are executed for the first timeat internal level and some of them fail. Theexpenses arise when the programmer has torectify all the defects uncovered from his pieceof code at the time of unit or componenttesting.2 External failures: it is the expense that occurswhen the defect is found by the customerinstead of the tester. These expenses are muchmore than what arise at internal level,especially if the customer gets unsatisfied orescalates the software failure.Cost of Software FailureWe know that a software failure is caused when:1 It displays lack of ability to keep up: thisgenerally happens when the software startsaging. As it grows old the size increasesbecause the easiest way of adding a feature isby adding new code without touching any partof code written earlier. Over a period of time itbecomes bulky and it becomes difficult toidentify the sections of code that need to bechanged.15

23P e r f o r m a n c e d ro p i s o b s e r v e d : E v e r yapplication generally slows down with age andtends to occupy more and more computermemory therefore it is better to switch to othersoftware.It doesn’t seem to be reliable: It is a known factthat every time when changes are made to thecode of the software to fix an error, moredefects are introduced in the system.Surprisingly, this is one of the major reasonsfor increased failure rates and in order to savesituation it is always better to ditch the projector give up bug fixing.Software Testing VS Quality AssuranceIn IT industry it is often observed that peoplegenerally don’t differentiate between the softwarequality assurance and software testing. Testers areoften looked upon as Software Quality Assuranceprofessionals because the objectives of softwaretesting as well as quality assurance are the same .i.e.to ensure that the software is of top quality.As the name suggests quality assurance processesare carried out to assure the quality of the product isin line with the requirement of the client. The qualityassurance professionals work on development andimplementation of all the necessary processes toensure that all the necessary procedures of softwaredevelopment lifecycle are followed correctly. Qualityassurance is a proactive activity that is focused on:1 Defect Prevention2 Processes3 Continuous improvement of this processesSoftware testing on the other hand is carried toidentify or uncover defect and errors in the software.It involves actual rigorous testing of the software tosee if there are any defects or variations from theclient’s requirement that needs to be fixed. Softwaretesting is a part of quality control process and itfocuses only on product oriented activities. Softwaretesting is carried out during the testing phase andonly defects are identified and not corrected in thisprocess. Fixing defects is not a part of softwaretesting.Quality Assurance VS Quality ControlAnother subject that is closely related to qualityassurance is quality control. People often getconfused between the two but there is a hugedifference. While quality assurance is all aboutpreventive activities, quality control focuses oncorrective processes.16

Here is what you need to understand: softwaretesting is a subset of quality control and qualitycontrol is a subset of quality assurance. The entirefocus of Quality assurance is on implementation ofprocesses and procedures that are required for theverification of the software under development andthe requirements of the client.Quality Assurance VS Quality ControlQuality control on the other hand deals with actualactivities that ensure that the product is beingdeveloped as per the defined requirements. It dealswith all the actions that are important to control andverify certain characteristics of the product includingtesting. Examination and testing of the products isthe most important aspect of quality control.Companies employ quality control team to identify ifthere is any product or service that does not meetthe company’s standard of quality. If there is an issuethe quality control team has the authority to stop theproduction of that product till the issue is resolved.Importance of Audit and InspectionAudit comprises of some very systematic processesthat define how the software testing is taking place inthe organization. The audit team examines all theprocesses that are conducted at the time of testing.IEEE defines audit as a review of documentedprocesses to ensure that the organization or a teamis following all the processes as per the definedstandards.Inspection can be a formal or an informal review ofsoftware requirement, designer or code. It isconducted by a team or an individual person otherthan the author to check if there are any violations ordeviations from the defined development standards.The following processes are considered as part ofInspection:1 Planning2 Overview Preparation3 Inspection Meeting4 Rework5 Follow up17

What Is Software Testing?carried out at all levels of software testing – unit,integration, system and acceptance.So, finally we come to the main topic that is softwaretesting itself. You have already understood themeaning of software testing and why it is importantwhile going through the previous sections. Here,from this section onwards we will take an in-depthlook at the subject, but before we move on let’s justrevise the definition of software testing.Software testing is nothing but the process ofassessing the functionality of software to ensure thatit is in line with the requirements of the customer.Testing is broadly classified into:1 Dynamic Testing: carried out by executing theprogram2 Static Testing: involves examination of codeand related documents.Dynamic and static testing is often used together.Black Box TestingBlack box testing focuses only on the functionality ofthe software. The tester does not look into theinternal details of the software. Black box testing isBlack Box TestingThe testing procedures for black box testing are verysimple. The tester only focuses on what the softwareis supposed to do. The tester is not supposed tofocus on how the software is managing the functioninternally. The test cases for black box testing arecreated keeping only the specifications andrequirements in mind. No test case is created tocheck the internal logic of the software. The testerjust feeds in valid and invalid inputs and checks theoutput for these values.18

White Box TestingUnlike black box testing, white box testing is carriedout in depth to the level of the source code. In thisform of testing the internal logic, its implementationand working is examined and the test cases arewritten to check the how the software is working atthe internal level. White box testing can be carriedout at the level of unit, integration and system level.White box testing is often used to detect internaldesign errors which are otherwise very difficult touncover however, this form of testing does not checkfor missing requirements or specifications.the code is executed at least once. The idea behindthis form of testing is to ensure that every statementin every block of code is executed at least once andthe results are observed. This form of testing is alsoreferred to as line coverage or segment coverageform of testing.The point to be noted here is that every statement isexecuted once which means that there may be someconditions in some blocks that may not get tested inthis manner. Therefore there is a possibility thatsome errors may go undetected in statementcoverage process.Decision CoverageDecision coverage or branch coverage deals withtesting of all true and false conditions of the code.The reason why it is also called branch coverage isbecause a branch is an outcome of decision. It isconsidered to be a more effective form of testingthan simple statement coverage. A decisionstatement can be:White Box TestingStatement CoverageStatement coverage is a form of testing in whichcode is tested in such a way that each statement of123An IF statementA loop control statement such as do-whileA statement that can have two or moreoutcomes also known as CASE statement.19

The good thing about decision coverage is that youare able to validate all branches in the code and it isable to check the efficiency of the code in a bettermanner than statement coverage approach.Condition CoverageCondition coverage testing is carried out to checkconditions which are generally Boolean expressionsand provide result in TRUE or FALSE. Conditioncoverage may or may not cover the entire decisioncoverage. In this process only those conditions thatreturn true or false are tested. The expressions thatreturns a Boolean condition generally plays a veryimportant role in the final decision. This is the reasonwhy condition coverage testing is carried out.Decision / Condition CoverageAs the name suggests decision/condition coveragemethodology includes testing all decisions and all thelogical conditions with all possible scenarios that cangenerate a true or false outcome. It is considered tobe a very strong way of testing software.For example:If (x true OR y true)ThenPrint (“Hello”)ElsePrint (“Bye”)Here, in this case there are four possible conditioncombinations:Testcase1: x true; y trueTestcase2: x true; y falseTestcase3: x false; y trueTestcase4: x false; y falseSimilarly, for 3 expressions there will be 8combinations of conditions.Multiple Condition CoverageMultiple condition coverage or conditioncombination coverage is carried out to check outputfor multiple combinations of conditions.20

Fundamentals of SoftwareTestingSoftware testing is a vast subject. There are softwareapplications and system engineered for numerousdomains and industries, and for a tester, everytesting project is a new challenge because he has tounderstand the client’s point of view and the domainbefore moving on with testing activities. From projectto project, a tester may have to change the testingmethodologies as well. It is therefore very importantto keep the fundamentals right. Getting thefundamentals right in the first place is biggestprerequisite to become successful in softwaretesting.Why Software Testing Is Necessary?An error, defect or a bug can be caused bydevelopers. It is not intentional but considering thecomplexity with which various software are beingdeveloped these days, it is quite possible for adeveloper to misunderstand and implement wronglogic and produce wrong code.Testing is necessary because it helps us in identifyingthe faults in software. Once these defects have beendetected they can be easily rectified and quality ofthe software can be improved. So, software testing isnecessary so that bug free applications can bedeveloped and delivered. When a company decidesto develop software for a client there are certainlegal, contractual and industry-specific requirementsbased on the deal is made. A quality consciouscompany will definitely include software testing in itsbest practices.It is difficult to say how much testing is enough butthe fact is that if testing is planned carefully andgood test cases are made then it is very muchpossible to deliver high quality software.Who Does The Software Testing?There is often a debate on who should actually testthe software. People often question that whydevelopers are not allowed to test. Well, a developergenerally checks his code several times before hesubmits it for testing and still in most cases it isnever error free because a developer is generallyblind to his own mistakes.A tester on the other hand looks at software fromthe point of view of the client. He is unbiased and hisfocus is only on the specifications and the21

requirements. So, a tester is able to look into areasthat a developer may have ignored. So, the testingshould always be carried out by independent testers.This approach does have some disadvantages. Whenthe development and testing teams are differentthere is often a communication gap and sometimes,developers become careless towards coding and donot revise their code because they think that it is all atester’s job thereby increasing the burden on thetester.Many times developers share their work amongsteach other and test each other’s work. This is knownas buddy testing. Every development team shouldhave dedicated testers and every project generallyhas at least one dedicated testing team. Somecompanies believe in having separate teams fordifferent types of testing, this means different teamsfor usability, performance, security and other formsof testing. Some companies believe in outsourcingsoftware testing work which means they hire a firmor independent testers or consultants to have a lookat and test their project.What Has To Be Really Tested?The tester should have a good understanding aboutthe project requirements. A fair idea about the realtim e scenar io where the softwa re will beimplemented can help the tester understand how tocarry out testing for the project. It is very importantto know what has to be really tested in order todevise a testing strategy.What Has To Be Really Tested?When Is The Software Testin

Software Testing book. I want to briefly share with you why we wanted to write this book for you and how you can get the best use out of it. Within the context of our Software Testing certification program we made a thorough research in Software Testing education s