Unit 1 defects classes
- 1. IT 8076 Software Testing UNIT – I Part -3 Dr. S. Roselin Mary, Professor & Head Department of Computer Science and Engineering (NBA Accredited) Anand Institute of Higher Technology, Chennai
- 2. Defect Classes : • Important – adapt a single classification scheme & apply it to all projects • Some defects will fit into more than one class or category – developers, testers & SQA – try to be consistent when recording defect data • Defect types & frequency of occurrence guide test planning & test design • Execution based testing strategies – strongest possibilities of detecting particular types of defect • Tests for new & modified software – designed to detect the most frequently occurring defects • Defect classes focusing execution based testing: » Requirement/specification defect class - Design defect class - Coding defect class - Testing defect class12/14/2019 2Dr.S.Roselin Mary, HOD/CSE
- 4. 1. Requirement / specification Defect classes: • Defects injected in early phase persist & very tough to remove at later phases • Requirement document – written in natural language with specification – Occurrence of ambiguous, contradictions, unclear, redundant &imprecise requirements • Specification document – similar – format specification language with tools – to prevent incorrect description of system behavior Functional Description defects – overall description of what the system does & how the system should behave is incorrect, ambiguous & incomplete Feature defects – feature descriptions – missing, incorrect, incomplete superfluous – Distinguishing character of a software component/system Feature Interaction defects – incorrect description of how the features should interact – Explain the example Interface description defects – defects that occur in the description of how the target software is to interface with external hardware, software & users • Blackbox based testing – at unit, integration, system & acceptance levels • Feature interaction & Interface description defects – detected using BB test at integration & system level tests 12/14/2019 4Dr.S.Roselin Mary, HOD/CSE
- 5. 2. Design defects: • Occur when system components, interaction between component to component, component to outside software/hardware are incorrectly designed • Covers defects in design of algorithm, control, logic, data elements, module interface description • Detailed design description – at pseudo level with processing steps, data structures, input output parameters & control structures Algorithmic & Processing defects: – Processing steps – incorrect – Calculation – not in order – missing/duplicated – Algorithm reuse – chosen an inappropriate algorithm Control, logic & sequence defects – Control defects occur when logic flow – incorrect – Branching – soon, late, incorrect – Unreachable psuedocode, improper nesting, improper procedure calls – Incorrect use of logic operators < , >, Boolean expression in branching operation Data defects – Incorrect design of data structures – Record – lacking a field, incorrect type for variable in record – Array – not have proper number of elements assigned – Reviews/data dictionary – reveal these defects 12/14/2019 5Dr.S.Roselin Mary, HOD/CSE
- 6. Module Interface description defects – Incorrect/inconsistent parameter types – Incorrect number of parameters/ ordering of parameters Functional description defects – Design maynot properly describe the functionality of a module – Incorrect/missing/unclear design elements – Detected during design review External Interface description defects – Incorrect design descriptions for interfaces external software, database & hardware devices – Improper sequence of commands, lack of proper messages & feedback messages 3. Coding defects • From errors in implementing the code • Closely related to design defect classes • Not understanding programming constructs • Transcription/omission Algorithmic & Processing defects – Unchecked overflow, underflow conditions – Comparing inappropriate data types – Conversion of datatype – Precedence of operators – Misuse of parentheses – Incorrect use of signs12/14/2019 6Dr.S.Roselin Mary, HOD/CSE
- 7. Control, logic and sequence defects – Case statements , iteration of loops, missing paths Typographical defects –syntax error Initialization defects – omission / incorrect initialization statements Dataflow defects – Variable should be initialized before its use – Don’t initialize twice before intermediate use Data defects – Incorrect implementation of data structures – record, array, flags, indices & constant sets Module Interface defects – similar to design defects Code documentation defects – Code documentation – doesn’t reflect what the program actually does – Incomplete/ ambiguous/incorrect/out of date External hardware, software interface defects – System calls, links to database, input output sequences, memeory usage, resource usage, interrupts, protocols & interfaces with build files • Design & coding defects – whitebox testing – dataflow, control, logic – Blackbox testing – decision tables, Boolean expression 12/14/2019 7Dr.S.Roselin Mary, HOD/CSE
- 8. 4. Testing defects • Defects in test plan, test cases, test harnesses, procedures Test Hareness defect – Test hareness / Scaffolding code – auxiliary code developed to test the software at the unit and integration levels – Should be carefully designed & tested – reuse – Subject to all other types of defects Test case design/ Test procedure defects – Incorrect/incomplete, missing, inappropriate test cases & procedures 12/14/2019 8Dr.S.Roselin Mary, HOD/CSE