Software testingObjectivesTopics coveredThe testing processTesting phasesDefect testingTesting process goalsThe software testing processTesting policiesSystem testingIntegration testingIncremental integration testingTesting approachesRelease testingBlack-box testingTesting guidelinesTesting scenarioSystem testsUse casesCollect weather data sequence chartPerformance testingStress testingComponent testingObject class testingWeather station object interfaceWeather station testingInterface testingSlide 28Interface typesInterface errorsInterface testing guidelinesTest case designRequirements based testingLIBSYS requirementsLIBSYS testsPartition testingEquivalence partitioningEquivalence partitionsSearch routine specificationSearch routine - input partitionsTesting guidelines (sequences)Slide 42Structural testingSlide 44Binary search - equiv. partitionsBinary search equiv. partitionsBinary search - test casesPath testingBinary search flow graphIndependent pathsTest automationA testing workbenchTesting workbench adaptationKey pointsSlide 55©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 1Software testing©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 2ObjectivesTo discuss the distinctions between validation testing and defect testingTo describe the principles of system and component testingTo describe strategies for generating system test casesTo understand the essential characteristics of tool used for test automation©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 3Topics coveredSystem testingComponent testingTest case designTest automation©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 4The testing processComponent testing •Testing of individual program components;•Usually the responsibility of the component developer (except sometimes for critical systems);•Tests are derived from the developer’s experience.System testing•Testing of groups of components integrated to create a system or sub-system;•The responsibility of an independent testing team;•Tests are based on a system specification.©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 5Testing phasesComponenttestingSystemtestingSoftware developerIndependent testing team©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 6Defect testingThe goal of defect testing is to discover defects in programsA successful defect test is a test which causes a program to behave in an anomalous wayTests show the presence not the absence of defects©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 7Testing process goalsValidation testing•To demonstrate to the developer and the system customer that the software meets its requirements;•A successful test shows that the system operates as intended.Defect testing•To discover faults or defects in the software where its behaviour is incorrect or not in conformance with its specification;•A successful test is a test that makes the system perform incorrectly and so exposes a defect in the system.©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 8The software testing processDesign testcasesPrepare testdataRun programwith test dataCompare resultsto test casesTestcasesTestdataTestresultsTestreports©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 9Only exhaustive testing can show a program is free from defects. However, exhaustive testing is impossible,Testing policies define the approach to be used in selecting system tests:•All functions accessed through menus should be tested;•Combinations of functions accessed through the same menu should be tested;•Where user input is required, all functions must be tested with correct and incorrect input.Testing policies©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 10System testingInvolves integrating components to create a system or sub-system.May involve testing an increment to be delivered to the customer.Two phases:•Integration testing - the test team have access to the system source code. The system is tested as components are integrated.•Release testing - the test team test the complete system to be delivered as a black-box.©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 11Integration testingInvolves building a system from its components and testing it for problems that arise from component interactions.Top-down integration•Develop the skeleton of the system and populate it with components.Bottom-up integration•Integrate infrastructure components then add functional components.To simplify error localisation, systems should be incrementally integrated.©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 12Incremental integration testingT3T2T1T4T5ABCDT2T1T3T4ABCT1T2T3ABTest sequence 1Test sequence 2Test sequence 3©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 13Testing approachesArchitectural validation•Top-down integration testing is better at discovering errors in the system architecture.System demonstration•Top-down integration testing allows a limited demonstration at an early stage in the development.Test implementation•Often easier with bottom-up integration testing.Test observation•Problems with both approaches. Extra code may be required to observe tests.©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 14Release testingThe process of testing a release of a system that will be distributed to customers.Primary goal is to increase the supplier’s confidence that the system meets its requirements.Release testing is usually black-box or functional testing•Based on the system specification only;•Testers do not have knowledge of the system implementation.©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 15Black-box testingIeInput test dataOeOutput test resultsSystemInputs causinganomalousbehaviourOutputs which revealthe presence ofdefects©Ian Sommerville 2004 Software Engineering, 7th edition. Chapter 23 Slide 16Testing guidelinesTesting guidelines are hints for the testing team to help them choose