During which stage is unit testing conducted?

Unit testing is conducted during the development stage of the software development lifecycle. This phase focuses on verifying individual components or modules of the application in isolation. The primary goal is to ensure that each unit functions correctly according to its specifications before it is integrated with other units.

By conducting unit testing during the development stage, developers can identify and fix issues early, which reduces the cost and effort associated with fixing defects later in the process. This is pivotal for maintaining code quality and ensuring that each part of the software behaves as intended when it is ultimately integrated with the larger application.

The other stages mentioned, such as integration testing, system-level testing, and physical interface testing, occur later in the development cycle, emphasizing the need for thorough unit testing first to establish a solid foundation for the subsequent stages. This systematic approach is key in minimizing the risk of failures as more components are integrated together.