軟件質(zhì)量與測(cè)試課件

軟件質(zhì)量與測(cè)試“SoftwareandCathedralsaremuchthesame:Firstwebuildthem,thenwepray!!!” -SamRedwine,Jr.Nomatterhowwellsoftwarehasbeendesignedandcoded,itwillinevitablystillcontaindefectsTestingistheprocessofexecutingaprogramwiththeintentoffindingdefectsA“successful”testisonethatfindserrors,notonethatdoesn’tfinderrors“Quality”isHardtoPinDown

（軟件質(zhì)量是很難衡量的）Concise,cleardefinitioniselusiveNoteasilyquantifiableManythingstomanypeople“You'llknowitwhenyouseeit”GoodQualitySoftwareHas…Understandability

（可理解的）TheabilityofareaderofthesoftwaretounderstanditsfunctionCriticalformaintenanceModifiability

（可修改的）TheabilityofthesoftwaretobechangedbythatreaderAlmostdefines"maintainability"GoodQualitySoftwareHas…Reliability

（可靠的）TheabilityofthesoftwaretoperformasintendedwithoutfailureIfitisn'treliable,themaintainermustfixitEfficiency

（高效的）TheabilityofthesoftwaretooperatewithminimaluseoftimeandspaceresourcesIfitisn'tefficient,themaintainermustimproveitGoodQualitySoftwareHas…Testability

（可測(cè)試的）TheabilityofthesoftwaretobetestedeasilyFinding/fixingbugsispartofmaintenanceEnhancements/additionsmustalsobetestedUsability

（可用的）Theabilityofthesoftwaretobeeasilyused(humanfactors)Noteasilyusedimpliesmoresupportcalls,enhancements,correctionsGoodQualitySoftwareHas…Portability

（可升級(jí)的）TheeasewithwhichthesoftwarecanbemadeusefulinanotherenvironmentPortingisusuallydonebythemaintainerNoticeallrelatedtomaintenancebutthesequalitiesneedtobeinstilledduringdevelopmentWhyTest?Nomatterhowwellsoftwarehasbeendesignedandcoded,itwillinevitablystillcontaindefectsTestingistheprocessofexecutingaprogramwiththeintentoffindingfaults(bugs)A“successful”testisonethatfindserrors,notonethatdoesn’tfinderrorsWhyTest?Testingcan“prove”thepresenceoffaults,butcannot“prove”theirabsenceButcanincreaseconfidencethataprogram“works”WhattoTest?Unit

test–testofsmallcodeunit:file,class,individualmethodorsubroutineIntegrationtest–testofseveralunitscombinedtoforma(sub)system,preferablyaddingoneunitatatimeSystem(alpha)test–testofasystemreleaseby“independent”systemtestersAcceptance(beta)test–testofareleasebyend-usersortheirrepresentativesWhentoTest? Early“Agileprogramming”developerswriteunittestcasesbeforecodingeachunitManysoftwareprocessesinvolvewriting(atleast)system/acceptancetestsinparallelwithdevelopmentOftenRegressiontesting:rerununit,integrationandsystem/acceptancetestsAfterrefactoringThroughoutintegrationBeforeeachreleaseDefiningaTestGoal–theaspectofthesystembeingtestedInput–specifytheactionsandconditionsthatleaduptothetestaswellastheinput(stateoftheworld,notjustparameters)thatactuallyconstitutesthetestOutcome–specifyhowthesystemshouldrespondorwhatitshouldcompute,accordingtoitsrequirementsTypesofsoftwaretestingUnittestingTestthebasicpieces,e.g.methodsIntegrationtestingCombinationsofunitsSystemtesting“Black-box”oracceptancetestingRegressiontestingMakesurechangesdon’tbreakanythingOthertypesoftestingObsessiontesting“I’llfixthisbugifit’sthelastthingIdo.”Aggressiontesting“Ifthisdoesn’twork,I’mgonnakillsomebody.”Depressiontesting“Ifthisdoesn’twork,I’mgonnakillmyself.”UnitTesting

（單元測(cè)試）UnitTestingOverviewUnittestingistestingsomeprogramunitinisolationfromtherestofthesystemUsuallytheprogrammerisresponsiblefortestingaunitduringitsimplementationEasiertodebugwhenatestfindsabug(comparedtofull-systemtesting)UnitTestingStrategiesBlackbox(specification-based)testingWhitebox(program-based)testing,akaglass-boxNormallyperformboth(notalternatives!)WhiteBoxTesting

（白盒測(cè)試）Testsuiteconstructedbyinspectingtheprogram(code)Lookatspecification(requirements,design,etc.)onlytodeterminewhatisanerrorAttempttoexerciseallstatements,allbranches,orallpaths(controlflowand/ordataflow)Intuition:Ifyounevertestedthatpartofthecode,howcanyouhaveanyreasontobelievethatitworks?WhiteboxApproaches

toUnitTestingExecuteall(reachable)statementsExecuteallbranchesoflogicaldecisions,includingboundariesofloopsExecuteall(feasible)controlflowpathsincombinationExecutealldataflowpaths(fromeachvariabledefinitiontoallitsuses)Usuallyappliedonlytoindividualsubroutinesratherthanlargerunit(duetocombinatorics)BlackBoxTestingTestsuiteconstructedbyinspectingthespecification(requirements,design,etc.),notthesourcecodeTestsunitagainstfunctionaland,sometimes,extra-functionalspecifications(e.g.,resourceutilization,performance,security)Attemptstoforcebehavior(outcome)thatdoesn'tmatchspecificationBlackboxApproachesto

UnitTestingFunctionaltesting–exercisecodewithvalidornearlyvalidinputforwhichtheexpectedoutcomeisknown(outcomeincludesglobalstateandexceptionsaswellasoutput)Exhaustivetestingusuallyinfeasible,soneedway(s)toselecttestcasesanddeterminewhen“done”testingChoosetestcasestoattempttofinddifferentfaultsEquivalencepartitioningBoundaryvalueanalysisAutomatedTestingTestingbyhandistedious,slow,error-proneandnotfunComputersaremuchlesseasilybo