Page 258 - Software and Systems Requirements Engineering in Practice

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ç ç # # H A P T E R ç ç ç 2 E Q U I R E M E N T S $ R I V E N ç 3 Y S T E M ç 4E S T I N G ç ç
H
RUNS ON THE ACTUAL TARGET SYSTEM SUCH THAT EACH REQUIREMENT CAN BE
SATISFIED 7HEN THE SYSTEM BEHAVIOR DOES NOT SATISFY THE REQUIREMENTS
DEFECT REPORTS ARE WRITTEN BY THE TESTERS SUCH THAT THE DEVELOPERS CAN
CORRECT THE DEFICIENCIES BEFORE THE PRODUCT IS RELEASED TO CUSTOMERS
3YSTEM TESTING IS A WELL DEFINED INDUSTRIAL PROCESS IN MANY CASES
HOWEVER IT REMAINS A MANUAL PROCESS 4YPICALLY TEST ENGINEERS DERIVE
THEIR TEST DATA THAT IS THEIR REQUIRED SYSTEM INPUT AND EXPECTED
OUTPUT INFORMATION FROM A VARIETY OF SOURCES INCLUDING TEXTUAL USE
CASE SPECIFICATIONS AND BUSINESS PROCESS RULES 4HEY THEN CREATE A SET
OF TEST PROCEDURES COMPRISING INDIVIDUAL TEST STEPS WHICH CAN BE
EXECUTED MANUALLY BY TEST EXECUTORS AGAINST THE SYSTEM UNDER TEST
354 7HENEVER AN AUTOMATED TEST EXECUTION ENVIRONMENT IS
AVAILABLE TESTS ARE TRANSLATED INTO EXECUTABLE TEST SCRIPTS 4HIS PROCESS
USUALLY OCCURS IN A LATE PHASE OF THE DEVELOPMENT PROCESS DURING
WHICH SYSTEM TESTERS STRIVE TO DISCOVER AS MANY DEFECTS AS POSSIBLE
I E NO CONFORMANCE WITH THE SPECIFIED REQUIREMENTS BEFORE THE
PRODUCT IS RELEASED TO THE MARKET
!S SYSTEM TESTING IS RELATIVELY EXPENSIVE AND OCCURS DURING THE
BACK END OF THE DEVELOPMENT PROCESS TEST TEAMS ARE USUALLY LARGE
AND OVERWORKED &OR MANY SYSTEMS WHERE END USER DISCOVERY OF
DEFECTS CAN HAVE SIGNIFICANT FINANCIAL OR SAFETY CONSEQUENCES AND
REGRESSION TESTING IS NECESSARY THE EXECUTION OF TESTS IS OFTEN HIGHLY
AUGMENTED BY AUTOMATED TOOLS I E TOOLS THAT ARE USED TO STIMULATE
THE 354 DISCOVER AND DOCUMENT DEFECTS 4HE AUTOMATIC GENERATION
OF TEST CASES CAN BE ACCOMPLISHED USING MODEL BASED TESTING -"4
APPROACHES TO BE DESCRIBED LATER IN THIS CHAPTER
$EFECTSõINõ2EQUIREMENTS
!LTHOUGH THIS CHAPTER IS FOCUSED ON SYSTEM TESTING THE h6v MODEL
ENVISIONS MANY STAGES OF TESTING REVIEW AND INSPECTION USED TO DETECT
DEFECTS )N MANY CASES DEFECTS IN REQUIREMENTS WILL BE DISCOVERED
DURING THESE DOWNSTREAM 6 6 ACTIVITIES #APERS *ONES REPORTS THAT
REQUIREMENTS IN 5 3 PROJECTS SEEM TO HAVE ABOUT TO DEFECTS BUGS
PER FUNCTION POINT ;*ONES = AND MOST FORMS OF TESTING ARE ONLY
ABOUT PERCENT EFFICIENT IN FINDING DEFECTS SO SOME REQUIREMENTS
DEFECTS WILL STILL BE PRESENT EVEN AT CUSTOMER DELIVERY !LSO EVEN GOOD
REQUIREMENTS WILL BE INCOMPLETE SO THERE WILL BE GAPS THAT CAN T BE
TESTED BECAUSE THE REQUIREMENTS ARE MISSING !BOUT PERCENT OF
ATTEMPTS TO FIX REQUIREMENTS DEFECTS ONCE THEY ARE IDENTIFIED WILL
ACCIDENTALLY INCLUDE NEW DEFECTS AS PART OF THE FIX ITSELF