Ch.4: QA in Context  QA and the overall development context Defect handling/resolution How alternative QA activities fit in process Alternative perspectives: verification/validation (V&V) view  Defect handling/resolution Defect logging and tracking are support activities How to handle depends on causal (root-cause) analysis Resolution: correct/re-verify or perform other action Improvement: break causal chain

Ch.4: Related Defect Handling Activities  Defect Handling Often parallel to testing Timely defect reporting  Where injected/found?  Type/severity/impact?  More detailed classification possible?  Consistent interpretation (failure vs. fault vs. error)  Defect DB Example Defect DB Example  Process and Tools formalized process (similar to configuration management) unit testing defects vs. later testing Tracking tools  status of defect

Ch.4: Related Defect Handling Activities  Defect analyses/quality models As follow up to defect handling. Data and historical baselines Goal: assessment/prediction/improvement Causal/risk/reliability/etc. analyses  Question: Why can we say that defect handling is not closely associated with defect prevention?  Details in Part IV.

Ch.4: QA in Software Processes  Mega-process: initiation, development, maintenance, termination.  Development process components (or phases): requirement, specification, design, coding, testing, release.  QA in waterfall process: Fig 4.1 (p.45) Testing has QA focus Defect prevention in early phases (error blocking) Defect removal in middle/late phases Defect containment in late phases Phase transitions: inspection/review/etc. QA scattered throughout the process

Ch.4: QA in Software Processes  Question: When can faults be injected in a software system? What phase are they MOST likely to be injected?  Question: There are practical obstacles to early fixing of injected defects. What are they?

Ch.4: QA in Software Processes  V-Model (Alternative to waterfall): QA in testing sub-phases (Fig 4.2, p.49)  Non-sequential processes  more user involvement => more validation  Iterative/Incremental: QA in iterations/increments – integration tests;  Spiral (which part to work on next based on risk analysis): selective QA on high-risk parts and operational testing;  Agile: test-driven development and inspect/test in pairs  QA in maintenance workflows: Focus on defect handling; Some defect containment activities for critical or highly-dependable systems; Collect data for QA activities in future releases  QA scattered throughout all processes!!!

Ch.4: V&V  Validation: w.r.t requirement (what?) Appropriate/fit-for-use/”right thing"? Scenario and usage inspection/testing; System/integration/acceptance testing; Beta testing and operational support. more external focus – linked with failures  Verification: w.r.t specification/design (how?) Correct/”doing things right"? Check conformance of software system to specifications Structural and functional testing; Inspections and formal verification. more internal focus

Ch 4: V & V Questions  Are the following verification or validation activities? activities that focus on providing continued service even when local problems exist safety assurance activities that prevent or reduce accident damage when an accident is unavoidable checking how one component works with another component determining whether a function behaves expectedly determining whether overall functions are implemented and implemented correctly detecting or preventing faults that are linked to failures

Ch.4: V&V vs DC View  Two views of QA: V&V view DC (defect-centered) view in this book Interconnected: mapping between V&V and DC views See Table 4.1 (p.51)

Ch.5: QA to QE  QA activities need additional support  Planning and goal setting  Management  When to stop?  Adjustment and improvement, etc.  All based on assessments/predictions  Assessment of quality/reliability/etc.: Data collection needed Analysis and modeling Providing feedback for management

Ch.5: QE Process  Overall process: Fig 5.1 (p.54)

Ch.5: QE Activities  Idea/activities similar to Quality Improvement Paradigm (QIP) understand, assess, package => feedback loop for improvement.  Major activities: Pre-QA planning (understand) QA: covered previously (Ch.3 & 4) (assess) Post-QA analysis and feedback (may be parallel instead of “post-") (package)

Ch.5: Pre-QA Planning  Setting quality goal(s): Identify quality views/attributes Select direct quality measurements Assess quality expectations vs. cost  Forming a QA strategy Individual strength/weakness/cost of QA Alternatives matched against goals Measurement/feedback planning:  define measurements & collect data  preliminary choices of models/analyses  feedback & follow up mechanisms, etc.

Ch.5: Analysis and Feedback  Measurement: Defect measurement as part of defect handling process Other related measurements  Analyses: quality/other models Data and historical baselines Goal: assessment / prediction / improvement Focus on defect / risk / reliability analyses  Feedback and follow up: Frequent feedback: assessments/predictions Possible improvement areas Used in management and improvement  Details in Part IV.

Ch.5: QE Context and Cost  QE activities in software processes: Different start/end time Different sets of activities and focuses In waterfall process: Fig 5.2 (p.61) In other processes: slight variations  QE activity/effort distribution/dynamics: Different focus in different phases Different levels (qualitatively) Different build-up/wind-down patterns In waterfall process: Fig 5.3 (p.63) In other processes: similar but more evenly distributed