Classification of Software Testing by Level of Detail

Unit testing focuses on testing individual components of the software separately. A component is the smallest testable part of the application. Unit testing is often performed by developers using the white-box testing method, allowing them to verify internal logic and functionality at the code level.

Integration testing evaluates the interaction between different modules of an application. It ensures that components work together as expected when combined. This phase helps detect interface defects and data flow issues between integrated parts.

System testing is performed on a fully integrated application to verify that the system as a whole meets the specified requirements. This level typically employs black-box testing techniques, focusing on functionality rather than internal code structure.

Acceptance testing is the final stage before software deployment. It ensures that the application meets business and user requirements. It is usually conducted in two phases:

• Alpha Testing: Performed within the company by specialized testers.

• Beta Testing: Conducted by independent testers or end-users to gather real-world feedback before release.

End-to-End testing simulates real-world usage by evaluating the complete workflow of an application. This approach ensures that all interconnected components function correctly, from start to finish. E2E testing often overlaps with system testing but focuses more on user scenarios.

Critical path testing is a subset of End-to-End testing that verifies the core functionalities essential for standard application use. It ensures that the most vital features operate correctly, minimizing risks in user-critical workflows.