Quality Management and Testing

What is Quality?

Software quality is the degree to which a product meets explicit and implicit requirements and user expectations. ISO 25010 defines eight quality attributes: functional suitability, performance efficiency, compatibility, usability, reliability, security, maintainability, and portability.

QA vs QC

Verification vs Validation

Verification — are we building the product right? Reviews, inspections, static analysis.
Validation — are we building the right product? Testing, user acceptance.

Testing Levels

1. Unit testing — individual functions or classes; usually automated with JUnit/pytest.
2. Integration testing — interactions between modules.
3. System testing — end-to-end against requirements.
4. Acceptance testing — by the customer; UAT, alpha, beta.

Testing Methods

• Black-box — test based on specification without knowing internals.
• White-box — test based on code structure (statement, branch, path coverage).
• Gray-box — combination.

Test Case Design Techniques

• Equivalence partitioning — group inputs with same behavior, test one per group.
• Boundary-value analysis — test at and around boundaries.
• Decision tables.
• State-transition testing.
• Use-case testing.

Types of Testing

• Functional, non-functional, regression, smoke, sanity, performance, load, stress, security, usability, compatibility, accessibility.

The V-Model

The V-model maps each development phase to a testing phase: requirements ↔ acceptance, design ↔ integration, module ↔ unit, implementation at the bottom.

Defect Management

1. Find defect (during testing or review).
2. Log in defect tracker (Jira, Bugzilla) with steps to reproduce, severity, priority.
3. Triage: accept, reject, defer.
4. Developer fixes.
5. Tester verifies fix.
6. Close.

Quality Standards

• ISO 9001 — generic quality management.
• ISO/IEC 25010 — software product quality.
• CMMI — capability maturity (levels 1-5).
• IEEE 829 — test documentation.

Reviews and Inspections

Reviews catch defects cheaply, before coding is complete. Types: walk-through (informal), peer review, formal inspection (Fagan), and audit.

Summary

Quality is built in through good process (QA) and verified through systematic testing (QC). Use both black-box and white-box techniques, test at all levels, and track defects through a disciplined process.

Important Questions

1. List ISO 25010 quality attributes.
2. Differentiate QA and QC.
3. What is the difference between verification and validation?
4. Explain the testing levels.
5. Compare black-box and white-box testing.
6. Explain equivalence partitioning and boundary-value analysis.
7. Describe the V-model.
8. Outline the defect life cycle.