02. testing throughout the software life cycle
- 2. TESTING THROUGHOUT THE SOFTWARE LIFE CYCLE TESTING IS NOT A STAND-ALONE ACTIVITY. IT HAS ITS PLACE WITHIN A SOFTWARE DEVELOPMENT LIFE CYCLE MODEL AND THEREFORE THE LIFE CYCLE APPLIED WILL LARGELY DETERMINE HOW TESTING IS ORGANIZED. THERE ARE MANY DIFFERENT FORMS OF TESTING. BECAUSE SEVERAL DISCIPLINES, OFTEN WITH DIFFERENT INTERESTS, ARE INVOLVED IN THE DEVELOPMENT LIFE CYCLE, IT IS IMPORTANT TO CLEARLY UNDERSTAND AND DEFINE THE VARIOUS TEST LEVELS AND TYPES. THIS CHAPTER DISCUSSES THE MOST COMMONLY APPLIED SOFTWARE DEVELOPMENT MODELS, TEST LEVELS AND TEST TYPES. MAINTENANCE CAN BE SEEN AS A SPECIFIC INSTANCE OF A DEVELOPMENT PROCESS. THE WAY MAINTENANCE INFLUENCES THE TEST PROCESS, LEVELS AND TYPES AND HOW TESTING CAN BE ORGANIZED IS DESCRIBED IN THE LAST SECTION OF THIS CHAPTER.
- 3. SOFTWARE DEVELOPMENT MODELS • V-MODEL BEFORE DISCUSSING THE V-MODEL, WE WILL LOOK AT THE MODEL WHICH CAME BEFORE IT. THE WATERFALL MODEL WAS ONE OF THE EARLIEST MODELS TO BE DESIGNED. IT HAS A NATURAL TIMELINE WHERE TASKS ARE EXECUTED IN A SEQUENTIAL FASHION. WE START AT THE TOP OF THE WATERFALL WITH A FEASIBILITY STUDYAND FLOW DOWN THROUGH THE VARIOUS PROJECT TASKS FINISHING WITH IMPLEMENTATION INTO THE LIVE ENVIRONMENT. DESIGN FLOWS THROUGH INTO DEVELOPMENT, WHICH IN TURN FLOWS INTO BUILD, AND FINALLY ON INTO TEST. TESTING TENDS TO HAPPEN TOWARDS THE END OF THE PROJECT LIFE CYCLE SO DEFECTS ARE DETECTED CLOSE TO THE LIVE IMPLEMENTATION DATE. WITH THIS MODEL IT HAS BEEN DIFFICULT TO GET FEEDBACK PASSED BACKWARDS UP THE WATERFALLAND THERE ARE DIFFICULTIES IF WE NEED TO CARRY OUT NUMEROUS ITERATIONS FOR A PARTICULAR PHASE.
- 5. ITERATIVE LIFE CYCLES TESTING WITHIN A LIFE CYCLE MODEL • IN SUMMARY, WHICHEVER LIFE CYCLE MODEL IS BEING USED, THERE ARE SEVERAL CHARACTERISTICS OF GOOD TESTING: • FOR EVERY DEVELOPMENT ACTIVITY THERE IS A CORRESPONDING TESTING ACTIVITY; • EACH TEST LEVEL HAS TEST OBJECTIVES SPECIFIC TO THAT LEVEL; • THE ANALYSIS AND DESIGN OF TESTS FOR A GIVEN TEST LEVEL SHOULD BEGIN DURING THE CORRESPONDING DEVELOPMENT ACTIVITY; • TESTERS SHOULD BE INVOLVED IN REVIEWING DOCUMENTS AS SOON AS DRAFTS ARE AVAIL ABLE IN THE DEVELOPMENT CYCLE.
- 6. TEST LEVELS • COMPONENT TESTING COMPONENT TESTING, ALSO KNOWN AS UNIT, MODULE AND PROGRAM TESTING, SEARCHES FOR DEFECTS IN, AND VERIFIES THE FUNCTIONING OF SOFTWARE (E.G. MODULES, PROGRAMS, OBJECTS, CLASSES, ETC.) THAT ARE SEPARATELY TESTABLE.
- 7. • INTEGRATION TESTING INTEGRATION TESTING TESTS INTERFACES BETWEEN COMPONENTS, INTERACTIONS TO DIFFERENT PARTS OF A SYSTEM SUCH AS AN OPERATING SYSTEM, FILE SYSTEM AND HARDWARE OR INTERFACES BETWEEN SYSTEMS. NOTE THAT INTEGRATION TESTING SHOULD BE DIFFERENTIATED FROM OTHER INTEGRATION ACTIVITIES. INTEGRATION TESTING IS OFTEN CARRIED OUT BY THE INTEGRATOR, BUT PREFERABLY BY A SPECIFIC INTEGRATION TESTER OR TEST TEAM. • SYSTEM TESTING SYSTEM TESTING IS CONCERNED WITH THE BEHAVIOR OF THE WHOLE SYSTEM/PRODUCT AS DEFINED BY THE SCOPE OF A DEVELOPMENT PROJECT OR PRODUCT. IT MAY INCLUDE TESTS BASED ON RISKS AND/OR REQUIREMENTS SPECIFICATION, BUSINESS PROCESSES, USE CASES, OR OTHER HIGH LEVEL DESCRIPTIONS OF SYSTEM BEHAVIOR, INTERACTIONS WITH THE OPERATING SYSTEM, AND SYSTEM RESOURCES. • ACCEPTANCE TESTING WHEN THE DEVELOPMENT ORGANIZATION HAS PERFORMED ITS SYSTEM TEST AND HAS CORRECTED ALL OR MOST DEFECTS, THE SYSTEM WILL BE DELIVERED TO THE USER OR CUSTOMER FOR ACCEPTANCE TESTING.
- 8. TEST TYPES: THE TARGETS OF TESTING • TESTING OF FUNCTION (FUNCTIONAL TESTING) FUNCTION (OR FUNCTIONALITY) TESTING CAN, BASED UPON ISO 9126 , BE DONE FOCUSING ON SUITABILITY, INTEROPERABILITY, SECURITY, ACCURACYAND COMPLIANCE. SECURITY TESTING, FOR EXAMPLE, INVESTIGATES THE FUNCTIONS (E.G. A FIREWALL) RELATING TO DETECTION OF THREATS, SUCH AS VIRUSES, FROM MALICIOUS OUTSIDERS. • TESTING OF SOFTWARE PRODUCT CHARACTERISTICS (NON-FUNCTIONAL TESTING) A SECOND TARGET FOR TESTING IS THE TESTING OF THE QUALITY CHARACTERISTICS, OR NON- FUNCTIONALATTRIBUTES OF THE SYSTEM (OR COMPONENT OR INTEGRATION GROUP). HERE WE ARE INTERESTED IN HOW WELL OR HOW FAST SOMETHING IS DONE. WE ARE TESTING SOMETHING THAT WE NEED TO MEASURE ON A SCALE OF MEASUREMENT, FOR EXAMPLE TIME TO RESPOND.
- 9. • TESTING OF SOFTWARE STRUCTURE/ARCHITECTURE (STRUCTURAL TESTING) THE THIRD TARGET OF TESTING IS THE STRUCTURE OF THE SYSTEM OR COMPONENT. IF WE ARE TALKING ABOUT THE STRUCTURE OF A SYSTEM, WE MAY CALL IT THE SYSTEM ARCHITECTURE. STRUCTURAL TESTING IS OFTEN REFERRED TO AS 'WHITE-BOX' OR 'GLASS-BOX' BECAUSE WE ARE INTERESTED IN WHAT IS HAPPENING 'INSIDE THE BOX'. • TESTING RELATED TO CHANGES (CONFIRMATION AND REGRESSION TESTING) THE FINAL TARGET OF TESTING IS THE TESTING OF CHANGES. THIS CATEGORY IS SLIGHTLY DIFFERENT TO THE OTHERS BECAUSE IF YOU HAVE MADE A CHANGE TO THE SOFTWARE, YOU WILL HAVE CHANGED THE WAY IT FUNCTIONS, THE WAY IT PERFORMS (OR BOTH) AND ITS STRUCTURE. HOWEVER WE ARE LOOKING HERE AT THE SPECIFIC TYPES OF TESTS RELATING TO CHANGES, EVEN THOUGH THEY MAY INCLUDE ALL OF THE OTHER TEST TYPES.
- 10. MAINTENANCE TESTING • IMPACT ANALYSIS AND REGRESSION TESTING IN ADDITION TO TESTING WHAT HAS BEEN CHANGED, MAINTENANCE TESTING INCLUDES EXTENSIVE REGRESSION TESTING TO PARTS OF THE SYSTEM THAT HAVE NOT BEEN CHANGED. A MAJOR AND IMPORTANT ACTIVITY WITHIN MAINTENANCE TESTING IS IMPACT ANALYSIS. DURING IMPACT ANALYSIS, TOGETHER WITH STAKEHOLDERS, A DECISION IS MADE ON WHAT PARTS OF THE SYSTEM MAY BE UNINTENTIONALLY AFFECTED AND THEREFORE NEED CAREFUL REGRESSION TESTING. • TRIGGERS FOR MAINTENANCE TESTING AS STATED MAINTENANCE TESTING IS DONE ON AN EXISTING OPERATIONAL SYSTEM. IT IS TRIGGERED BY MODIFICATIONS, MIGRATION, OR RETIREMENT OF THE SYSTEM. MODIFICATIONS INCLUDE PLANNED ENHANCEMENT CHANGES (E.G. RELEASE-BASED), CORRECTIVE AND EMERGENCY CHANGES, AND CHANGES OF ENVIRONMENT, SUCH AS PLANNED OPERATING SYSTEM OR DATABASE UPGRADES, OR PATCHES TO NEWLY EXPOSED OR DISCOVERED VULNERABILITIES OF THE OPERATING SYSTEM.