SOFTWARE QUALITY ASSURANCE.ppt
- 1. 1 Software Quality Assurance Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 2. 2 What is Software Quality Assurance? Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 3. 3 What is Quality? Quality – developed product meets it’s specification Problems: • Development organization has requirements exceeding customer's specifications (added cost of product development) • Certain quality characteristics can not be specified in unambiguous terms (i.e. maintainability) • Even if the product conforms to it’s specifications, users may not consider it to be a quality product (because users may not be involved in the development of the requirements) Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 4. 4 Quality Management – ensuring that required level of product quality is achieved • Defining procedures and standards • Applying procedures and standards to the product and process • Checking that procedures are followed • Collecting and analyzing various quality data Problems: • Intangible aspects of software quality can’t be standardized (i.e elegance and readability) What is Quality Management? Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 5. 5 What are SQA, SQP, SQC, and SQM? SQA includes all 4 elements… • Software Quality Assurance – establishment of network of organizational procedures and standards leading to high- quality software 2. Software Quality Planning – selection of appropriate procedures and standards from this framework and adaptation of these to specific software project 3. Software Quality Control – definition and enactment of processes that ensure that project quality procedures and standards are being followed by the software development team 4. Software Quality Metrics – collecting and analyzing quality data to predict and control quality of the software product being developed Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 6. 6 Software Development Standards SDS Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 7. 7 Why are Standards Important? • Standards provide encapsulation of best, or at least most appropriate, practice • Standards provide a framework around which the quality assurance process may be implemented • Standards assist in continuity of work when it’s carried out by different people throughout the software product lifecycle Standards should not be avoided. If they are too extensive for the task at hand, then they should be tailored. Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 8. 8 SDS a Simplistic approach In most mature organizations: • ISO is not the only source of SDS • Process and Product standards are derived independently • Product standards are not created by SQA Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 9. 9 Quality Models Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 10. 10 ISO - 9001 Elements • Quality System Requirements • Management Responsibility • Quality system • Contract review • Design Control • Document control • Purchasing • Purchaser supplied product • Product identification and traceability • Process control • Inspection and testing • Inspection, measuring and test equipment • Inspection and test status • Control of non-conforming product • Corrective action • Handling, storage, preservation, packaging and shipping • Quality records • Internal quality audits • Training • Servicing • Statistical techniques • Software Quality Responsibilities • Management Responsibility • Quality system • Contract review • Design Control • Document control • Purchasing • - • Product identification and traceability • Process control • Inspection and testing • - • Inspection and test status • - • Corrective action • - • Quality records • Internal quality audits • Training • - • Statistical techniques Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 11. 11 Capability Maturity Model KPA’s(CMM) Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 12. 12 CMM Integration Model Architecture Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 13. 13 Quality Improvement – The Wheel of 6Sigma Six Sigma Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 14. 14 Quality Improvement – Six Sigma Process • Visualize – Understand how it works now and imagine how it will work in the future • Commit – Obtain commitment to change from the stakeholders • Prioritize – Define priorities for incremental improvements • Characterize – Define existing process and define the time progression for incremental improvements • Improve – Design and implement identified improvements • Achieve – Realize the results of the change Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 15. 15 Continuity and Independence of SQA • Software Quality Assurance team must be independent in order to take an objective view of the process and report problems to senior management directly • If prescribed process is inappropriate for the type of software product which is being developed, then it should be tailored • The standards must be upheld no matter how small the task. Prototyping doesn’t mean no standards. It means tailored standards. • Quality is FREE, if it’s Everyone’s Responsibility! Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 16. 16 Software Quality Planning Element II Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 17. 17 Software Quality Plan • Tailoring - SQP should select those organizational standards that are appropriate to a particular product • Standardization - SQP should use (call out) only approved organizational process and product standards • If new standards are required a quality improvement should be initiated • Elements - SQP elements are usually based on the ISO-9001 model elements • SQP is not written for software developers. It’s written for SQE’s as a guide for SQC and for the customer to monitor development activities • Things like software production, software product plans and risk management should be defined in SDP, IP • Quality Factor’s shouldn’t be sacrificed to achieve efficiency. Don’t take the job if quality process can’t be upheld Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 18. 18 Software Quality Control Element III Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 19. 19 Methods of Software Quality Control SQC involves overseeing the software development process to ensure that the procedures and STD’s are being followed The following activities constitute SQC: • Quality Reviews - in-process reviews of processes and products Reviews are the most widely used method of validating the quality of processes and products. Reviews make quality everyone's responsibility. Quality must be built-in. SQE is responsible for writing Quality Engineering Records (QERs) documenting their participation in these reviews. • Tests - end-result verifications of products. These verifications are conducted after the software has been developed. Test procedures are followed during conduct of these activities. SQE is responsible for keeping the logs and some times for writing the test report. • Quality Audits - in-process verifications of processes. These audits are conducted periodically (twice a month) to assess compliance to the process STD’s. Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 20. 20 Quality Reviews • Peer reviews - reviews of processes and products by groups of people. These reviews require pre-review preparation by all participants. If a participant is not prepared, then the review is not effective. This type of review requires participation of the SQE, moderator, recorder, author(s), and one or more critical reviewers. All issues found during these reviews are documented on AR forms. • Walkthroughs - reviews of products by groups of people mostly without preparation. For example a requirements traceability review is a walkthrough. It involves tracing a requirement from customer requirements to the test procedures. All issues found during these reviews are documented on CAR forms. • Desk inspections - reviews of products by individuals. These reviews involve people reviewing products by themselves (not in a group) and then submitting their comments to the author(s). The issues found during these reviews are treated in informal manner. Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 21. 21 Tests • Engineering Dry-run - test conducted by engineering without SQE. These tests include Unit Tests and engineering dry-runs of the formal tests. These engineering dry- runs are used to verify correctness and completeness of the test procedures. Also, these is the final engineering verification of the end-product before sell-off to SQE. All issues found during these tests are documented on STR forms. • SQE Dry-run - test conducted by SQE. These tests include PQT, FAT and SAT dry- runs. These tests are used to verify the end-product before the formal test with the customer. An SQE is sometimes responsible for writing the test report. However, if a separate test group is available, then SQE is relived of this obligation. All issues found during these tests are documented on STR forms. • TFR - test conducted as “RFR - run-for-record” with the SQE and the customer. These tests include FAT and SAT. These tests are conducted to sell the end-product off to the customer. SQE is present at all such tests. All issues found during these tests are documented on STR forms. Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 22. 22 Quality Audits • SQE Audits - audits conducted by SQE to verify that the process STD’s are being followed. Examples of these audits are IPDS compliance, Configuration Control, and Software Engineering Management. All findings for these audits are documented on QER forms. The results of the audits are distributed to the next level of management (above project level). If the issue(s) are not fixed then the findings are elevated to upper management. • Independent Audits - audits conducted by ISO generalists or other independent entities to verify that the process STD’s are being followed. These audits are usually conducted on a division/facility level. The results of these audits are distributed to upper management. Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 23. 23 Software Quality Metrics Element IV Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 24. 24 Metrics Collection • Software measurement - the process of deriving a numeric value for some attribute of a software product or a software process. Comparison of these values to each other and to STD’s allows drawing conclusions about the quality of software products or the process. • The focus of the metrics collecting programs is usually on collecting metrics on program defects and the V&V process. • Metrics can be either Control Metrics or Predictor Metrics • Most of the “Ilities” can not be measured directly unless there’s historical data. Instead tangible software product attributes are measured and the “Ility” factors are derived using predefined relationships between measurable and synthetic attributes. • The boundary conditions for all measurements should be established in advance and then revised once a large databank of historical data has been established Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 25. 25 The Process of Product Measurement 1. Decide what data is to be collected 2. Assess critical (core) components first 3. Measuring component characteristics might require automated tools 4. Look for consistently (unusually only works in a factory) high or low values 5. Analysis of anomalous components should reveal if the quality of product is compromised Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 26. 26 Predictor and Control Metrics Examples of Predictor Analysis: • Code Reuse: SLOC = ELOC = Ported Code • Nesting Depth: ND > 5 = Low Readability • Risk Analysis: # STR P1 > 0 at SAT = Low Product Reliability Examples of Control Analysis: • STR aging: Old STRs = Low Productivity • Requirements Volatility: High Volatility = Scope Creep Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 27. 27 Software Product Metrics There are two categories of software product metrics: 1. Dynamic metrics – this metrics is collected by measuring elements during program’s execution. This metrics help to asses efficiency and reliability of a software product. The parameters collected can be easily measured (i.e. execution time, mean time between failures) 2. Static metrics – this metrics is collected by measuring parameters of the end products of the software development. This metrics help to asses the complexity, understandability, and maintainability of a software product. The SLOC size and ND are the most reliable predictors of understandability, complexity, and maintainability. Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 28. 28 Examples of Software Metric – Chapter 24 Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 29. 29 Examples of OO Software Metric – Chapter 24 Prepared by, Dr.T.Thendral, Assistant Professor, SRCW
- 30. 30 The end Prepared by, Dr.T.Thendral, Assistant Professor, SRCW