Quality Assurance / Testing
Systematic process of checking software for defects, security issues and quality requirements through manual and automated tests.
Quality assurance (QA) and testing are essential parts of professional software development. Bugs in production cost many times more than early testing. Modern QA combines automated tests at several levels with targeted manual testing to keep software reliable, secure and usable.
What is Quality Assurance / Testing?
Software testing is the systematic process of checking software for defects (bugs), security issues, performance problems and requirement compliance. Levels include: unit tests (single functions in isolation), integration tests (interaction between components), end-to-end tests (E2E) that simulate real user scenarios, and performance tests under load. QA goes beyond testing and includes code reviews, static analysis, coding standards and process audits. The test pyramid recommends many unit tests, fewer integration tests and few E2E tests.
How does Quality Assurance / Testing work?
In a modern CI/CD pipeline, tests run automatically on every commit. Unit tests run in seconds and give immediate feedback. Integration tests check database access, API calls and service interaction. E2E tests (e.g. Cypress, Playwright) simulate real user flows in the browser. Performance tests (e.g. k6, JMeter) test under load. Security tests (SAST, DAST) find vulnerabilities. Code coverage measures how much code is covered by tests.
Practical Examples
E-commerce shop: Automated E2E tests run the full checkout including payment on every release to avoid revenue loss from bugs.
Banking software: Extensive regression tests ensure new features do not break existing booking processes. Security testing covers every change.
SaaS platform: API contract tests ensure backend changes do not break the frontend. Consumer-driven contracts secure microservice communication.
Mobile app: Automated UI tests on real devices (BrowserStack, Sauce Labs) check the app on different screen sizes and OS versions.
Legacy modernisation: Characterization tests document existing behaviour as a safety net before refactoring.
Typical Use Cases
Continuous integration: Automated tests as a quality gate in CI/CD
Regression testing: Ensuring new changes do not break existing behaviour
Security testing: Finding vulnerabilities via SAST, DAST and penetration tests
Performance testing: Validating that the system handles required load
Acceptance testing: Checking that the software meets business requirements
Advantages and Disadvantages
Advantages
- Early detection: Bugs are found before they cause damage in production
- Cost: Fixing a bug in development is 10–100x cheaper than in production
- Confidence: Automated tests give the team confidence to change and release
- Documentation: Tests document expected behaviour
- Speed: Automated tests enable frequent, safe releases
Disadvantages
- Initial effort: Building test infrastructure and writing tests takes time
- Maintenance: Tests must be updated when the software changes
- False security: High coverage does not guarantee all important scenarios are tested
- Flaky tests: Unstable tests that fail randomly undermine trust in the suite
Frequently Asked Questions about Quality Assurance / Testing
How much code coverage do you need?
Manual or automated testing?
What is TDD (Test-Driven Development)?
Related Terms
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