lecture11-软件质量度量课件.ppt

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1、SoftwareMetricsLecture10MeasuringSoftwareQuality清华大学软件学院2004年5月18日1EstimateNo.ofTestCasesTime(availabletimeavailablestaff)/(averagetimetoprepareatestcase)Howmanytestcasesdoweneed?Cost(availablebudget)/(averagepreparationcostpertestcase)Selecttheminimumnumberofthetwo2TestCoverageMetricsCoverag

2、eofwhat?StatementcoverageBranchcoverageComponent/ModulecoverageSpecificationcoverageGUIcoverage…3RemainingDefectsMetricsNsisalreadyknown;ndandnsaremeasuredforacertainperiodoftimeTwotestingteamswillbeassignedtotestthesameproduct.4SoftwareQualitySoftwareQualityModelsSoftwareQualityMetricsContent

3、s5Section1SoftwareQuality6WhatisQuality?Qualitypopularviews:ZerodefectsSomething“good”butnotquantifiableSomethingluxuryandclassyQualityprofessionalviews:Conformancetorequirement(Crosby,1979)Fitnessforuse(Juran,1970)7WhatisSoftwareQuality?/1Conventionaldefinitions:ConformancetorequirementThereq

4、uirementsareclearlystatedandtheproductmustconformtoitAnydeviationfromtherequirementsisregardedasadefectAgoodqualityproductcontainsfewer“bugs”FitnessforuseFitto“user”expectations:meetuser’sneedsAgoodqualityproductprovidesbetterusersatisfaction8WhatisSoftwareQuality?/2Variousviewpoints:Conforman

5、cetocustomers’requirementsRequirement,designanddevelopmentqualityProcessqualityvs.end-productqualityInternalvs.externalcharacteristicsRelativity:advantageoversimilarproductsConformance:conformancetostandards9SoftwareQuality:DifficultiesNeedtoaccountfor“creativity”inthe“design”oftheproductandth

6、e“requirements”ratherthantheproductitself.Kindofart…Whichonehasahigherquality?LeonardoMonaLisa(1479)PabloPicasso10SoftwareQualityInISO9126ThetotalityoffeaturesandcharacteristicsofasoftwareproductthatbearonitsabilitytosatisfystatedorimpliedneedsGB/T16260――1996与软件产品满足明确或隐含需求的能力有关的特征和特性的总和。11Soft

7、wareQuality:ClassificationByobservability:InternalqualityExternalqualityByprocess:DesignqualityImplementationqualityTestqualityMaintenancequality12Section2SoftwareQualityModels13ModelingSoftwareQualitySelectingsomeattributes(orfactors)S