Testing is executable or manual verification that checks software behavior against expected outcomes. Its central discipline is doubt: deliberately looking for evidence that code is wrong rather than confirming what already seems correct. Strong testing supports durable software by exposing defects before users discover them. section 9.3 section 7.1.3
Choose test types according to the behavior and boundary being verified:
- Unit tests verify the smallest pieces of code, such as methods and functions, in isolation; they are automated and commonly run locally or in CI/CD pipelines. section 9.3
- Integration tests validate interactions between modules or services. section 9.3
- Functional tests exercise complete business scenarios from a user's point of view. section 9.3
- Acceptance tests verify that delivered features meet client requirements. section 9.3
Testing a weight converter
A WeightConverter converts pounds to kilograms and rejects negative input. Focused unit tests check a normal conversion, zero, and the expected IllegalArgumentException for a negative value. The test names describe the action and expected result, making the behavior readable while checking both valid and invalid paths. section 9.3
Table 9.3 Main types of tests
|
Type of test
|
Purpose / Description
|
Common Frameworks / Tools
|
|---|---|---|
|
Unit tests
|
Verify the smallest pieces of code (methods and functions) in isolation. They are fully automated, run locally, and in CI/CD pipelines.
|
Java: JUnit, TestNG Python: PyTest, unittest JavaScript: Jest, Mocha, Jasmine C#:/.NET: xUnit, NUnit, MSTest
|
|
Integration tests
|
Validate how modules or services interact. They are mostly automated, run locally, and in CI/CD pipelines.
|
Java: Spring Test, Arquillian Python: PyTest + fixtures JavaScript: SuperTest, Cypress .NET: MSTest, SpecFlow
|
|
Functional tests
|
Test complete business scenarios from a user’s point of view. They are manual or automated.
|
Selenium, Cypress, Playwright, Robot Framework
|
|
Acceptance tests
|
Verify that newly delivered features meet client requirements. They are manual or automated.
|
Multilanguage: Cucumber (Gherkin) Python: Behave NET: Reqnroll
|
|
Regression tests
|
Essential tests run after changes to ensure nothing broke. They can be automated or manual and typically replay key unit, integration, acceptance, and functional tests to confirm stability after updates.
|
Uses the same tools as unit, integration, acceptance, and functional tests.
|
|
Performance tests
|
Performance tests measure speed, response time, scalability, and resource usage using load, stress, or endurance testing. They are usually fully automated but not included in the regular CI/CD pipeline.
|
JMeter, Gatling, Locust, k6, Artillery
|
|
Security tests
|
Detect vulnerabilities such as injections, XSS, or weak authentication. Automated through static code analysis tools, such as SonarQube, and dynamic testing tools, often complemented by manual penetration testing.
|
OWASP ZAP, Burp Suite, Snyk, Bandit
|
|
Chaos engineering/resilience testing
|
Intentionally inject failures or adverse conditions to verify that the system remains stable and recovers as expected under real-world turbulence. Manual or automated, but used selectively in staging or carefully controlled production environments.
|
Chaos Mesh, LitmusChaos
|
|
Accessibility tests
|
Ensure compliance with accessibility standards. Automated and manual tools detect violations, and testers confirm usability.
|
Axe, Lighthouse, Pa11y, Deque tools
|
|
Exploratory tests
|
Manual tests. Discover UX flaws or unexpected behavior. Rely on tester observation and creative exploration.
|
Compare test types by purpose, scope, automation, execution context, and representative frameworks. section 9.3
