UNIT-1 software testing chapter (must learn)

Software testing

1. UNIT-I
IntroductiontosoftwareQualityandAssurance
•Thesoftwarequalitychallenge
•Softwarequality
•Softwarequalityfactors
•Managementanditsroleinsoftwarequalityassurance

2. TheSoftwareQualityChallenges
•ThisChapterisessentiallyabouttwomajortopics:
•Theuniquenessofsoftwarequalityassurance
•TheenvironmentsforwhichSQA(SoftwareQualityAssurance)
methodsare developed

3. Introduction
•WhystudyQualityAssuranceandTesting?
•Withallthemethodologywars,numerousprocesses,hugenumber
oftoolstoassistinsoftwaredevelopment,whythis separatetopic?
•Whatmakesitimportantthatitdeservesseparatetreatment?
•Whydosomanycompaniesadddisclaimerstotheirsoftware?
•Don’twarrantythedocumentation…
•Notresponsiblefordirect,indirect,consequential,loss?

4. TheSoftwareQualityChallenges
1.Identifytheuniquecharacteristicsofsoftwareasaproductandas
processthat justifyseparate treatmentof itsquality issues.
2.Recognizethecharacteristicsofthesoftwareenvironmentwhere
professionalsoftwaredevelopmentandmaintenancetakeplace

5. SoftwareProductv/sIndustrialProduct
1.Highcomplexity
•Thepotentialwaysinwhichasoftwareproductcanbeusedwith
differentdata/datapathsreflectingdifferentincomingdatais
almostinfinite.
•Mannerinwhichindustrialproductscanbeusedareusuallywell-
defined.
•Thinkaboutsoftware:everyloopwithdifferentvaluesofdata
reflectsadifferentopportunitytoseesoftwarefail.

6. SoftwareProductv/sIndustrialProduct
2.Invisibilityoftheproduct
•Inanindustrialproduct,missingpartsareobvious.
•Something missing?Easilyidentified.
•Notsoinsoftwareproducts.
•Maynotbenoticeableforyears–ifatall!

7. SoftwareProductv/sIndustrialProduct
3.Opportunitiestodetectdefects(“bugs”)??
1.ProductDevelopment:
•Industrial:testproduct;voltages;performance;strength;
size;….ready to distributeto markets
•ComputerSoftware:onceprototypeandsystemtestingare
concluded,product isready for deployment
2.ProductProductionPlanning:
•Industrial:Oftenneednewtoolingapproaches,assemblylines,
newmanufacturing processes.
•Resultsinadditional‘looks’atproducts
•Onecouldsaythatthereisabetterchancetodiscover
defects
•Computer Software:Norealadditional‘look-see.’
•Packagesshrink-wrapped,printed,distributedtopublic

8. SoftwareProductv/sIndustrialProduct
3.ProductManufacturing:
•Industrial: Usuallydefectsuncoveredhere;easilyfixed.
•Typicalburn-inproblems;anotherviewofproduct;
stabilizes.
•Theserepresentadditionalopportunitiestodiscoverdefects.
•ComputerSoftware:
•Wemerelycopyright,printcopiesofsoftwareandmanuals
•Norealchanceforadditionalqualityviews
•Norealchancefordiscoveringadditionaldefects

9. SoftwareProductv/sIndustrialProduct

10. SQAEnvironment

11. CharacteristicsofSQAEnvironment

12. CharacteristicsofSQAEnvironment

13. CharacteristicsofSQAEnvironment

14. CharacteristicsofSQAEnvironment

15. CharacteristicsofSQAEnvironment

16. CharacteristicsofSQAEnvironment

17. CharacteristicsofSQAEnvironment

18. CharacteristicsofSQAEnvironment

19. CharacteristicsofSQAEnvironment

20. CharacteristicsofSQAEnvironment

21. CharacteristicsofSQAEnvironment

22. Whatissoftware?

23. SoftwareErrors,FaultsandFailures

24. SoftwareErrors,FaultsandFailures

25. CausesofSoftwareErrors

26. CausesofSoftwareErrors

27. CausesofSoftwareErrors

28. CausesofSoftwareErrors

29. CausesofSoftwareErrors

30. CausesofSoftwareErrors

31. CausesofSoftwareErrors

32. CausesofSoftwareErrors

33. CausesofSoftwareErrors

34. CausesofSoftwareErrors

35. SoftwareQuality

36. SoftwareQualityFactors
ItscalledMcCall’sfactormodel
A.Correctness:Itdealwithrequirementsthataredefinedin
alistofthesoftwaresystem’srequiredoutputs,suchas
outputmission,accuracyofthoseoutputs,accuracyof
thoseoutputs,up-to-dateoftheinformation,availability
oftheinformation,standardsforcodingand
documenting.
B.Reliability:Itdealwithfailurestoprovideservice.They
determinethemaximumallowedsoftwaresystemfailure
rate,andcanrefertotheentiresystemortooneormore
ofitsseparatefunctions.

37. SoftwareQualityFactors
C.Efficiency:Itdealwiththehardwareresourcesneededto
performallthefunctionsofthesoftwaresystemin
conformancetoallotherrequirements.
D.Integrity:Itdealwiththesoftwaresystemsecurity,thatis,
requirementstopreventaccesstounauthorizedpersons
E.Usability:Itdealwiththescopeofstaffresourcesneeded
totrainanewemployeeandtooperatethesoftware
system.

38. SoftwareQualityFactors
F.Maintainability:Itdeterminetheeffortsthatwillbe
neededbyusersandmaintenancepersonneltoidentify
thereasonsforsoftwarefailures,tocorrectthefailures,
andtoverifythesuccessofthecorrections.
G.Flexibility:Thecapabilitiesandeffortsrequiredtosupport
adaptivemaintenanceactivitiesarecoveredbythe
flexibilityrequirements.
H.Testability:Itdealwiththetestingofaninformation
systemaswellaswithitsoperation.

39. SoftwareQualityFactors
I.Portability:Ittendtotheadaptationofasoftwaresystem
tootherenvironmentsconsistingofdifferenthardware,
differentoperatingsystems.
J.Reusability:Itdealwiththeuseofsoftwaremodules
originallydesignedforoneprojectinanewsoftware
projectcurrentlybeingdeveloped.
K.Interoperability:Itfocusoncreatinginterfaceswithother
softwaresystemsorwithotherequipmentfirmware.

40. SoftwareQuality
Tillnowwediscussed,
•softwarequalitychallenge
•SoftwareProductv/sIndustrialProduct
•CharacteristicsofSQAEnvironment
•Whatissoftware?
•SoftwareErrors,FaultsandFailures
•CausesofSoftwareErrors
•SoftwareQualityFactors

41. SoftwareQualityAssurance

42. ImplementtheQualityAssurance

43. ImplementtheQualityAssurance
Step1:DevelopSQAplan

44. ImplementtheQualityAssurance
Step2:Preparation

45. ImplementtheQualityAssurance
Step3:ReviewtheProcess

46. RoleofManagementinQA
Basically, a three-level structure of management exists in
softwaredevelopment organizations−
•Topmanagement
•Departmentmanagement
•Projectmanagement

47. RoleofManagementinQA
1.TOPMANAGEMENTRESPONSIBILITIES
Following are the responsibilities of the top management in
ensuringSoftware Quality −
•Assure the quality of the company’s software products and
softwaremaintenance services
•Communicate the importance of the product and service
quality in addition to customer satisfaction to employees at
alllevels
•Assure satisfactory functioning and full compliance with
customerrequirements
•Ensurethatqualityobjectivesareestablishedforthe
organization’sSQAsystemandthatitsobjectivesare
accomplished

48. RoleofManagementinQA
•Initiate planning and oversee implementation of changes
necessary to adapt the SQA system to major internal as
well as external changes related to the organization’s
clientele,competition, andtechnology
•Intervene directly to support resolution of crisis situations
andminimize damages
•Ensure the availability of resources required by SQA
systems

49. RoleofManagementinQA
The following steps can be taken by the top management to
fulfillits responsibilities −
•Establishing and updating the organization’s software
qualitypolicy.
•Assigning one of the executives such as Vice President for
SQAtobein chargeof softwarequality issues
•Conducting regular management reviews of performance
withrespect tosoftware qualityissues

50. RoleofManagementinQA
2.DepartmentManagementResponsibilities
Middlemanagement’squalityassuranceresponsibilities
include−
Management of the software quality management system
(qualitysystem-related tasks)
Managementoftasksrelatedtotheprojectsandservices
performedbyunitsorteamsunderthespecificmanager’s
authority(project-relatedtasks)

51. RoleofManagementinQA
3.Projectmanagementresponsibilities
Mostprojectmanagementresponsibilitiesaredefinedin
proceduresandworkinstructions;theprojectmanageristhe
personin-chargeofmakingsurethatalltheteammembers
complywiththesaidproceduresandinstructions.
Histasksincludeprofessionalhands-onandmanagerialtasks,
particularlythefollowing−
•Professionalhands-ontasks
•Managementtasks

52. SoftwareQualityv/sQualityAssurance
Quality control is a set of activities carried out with the main
objective of withholding products from shipment if they do
notqualify.
In contrast, quality assurance is meant to minimize the costs
of quality by introducing a variety of activities throughout the
development and maintenance process in order to prevent
the causes of errors, detect them, and correct them in the
early stages of development. As a result, quality assurance
substantiallyreducestheratesofnonqualifyingproducts.

53. Verificationv/sValidation
Verification refers to the set of tasks that ensure that
softwarecorrectlyimplementsaspecificfunction.
Validation refers to a different set of tasks that ensure that
the software that has been built is traceable to customer
Requirements.