What is the primary purpose of unit testing?

The primary purpose of unit testing is to test individual components or functions of a program. Unit tests focus on the smallest testable parts of an application, often individual methods or classes, to ensure that they perform as expected. By isolating these components, developers can validate that each part of the application behaves correctly in isolation, which helps in identifying and fixing bugs early in the development process.

This approach fosters a more modular code structure since developers can ensure that each unit operates independently and as intended. If a unit fails a test, it indicates that there’s an issue specifically within that component, making it easier to pinpoint and resolve problems without affecting the entire system. Additionally, unit testing contributes to more reliable and maintainable code since developers receive immediate feedback on new changes or refactorings.

While other types of testing, such as integration testing or system testing, assess how components work together or the overall application behavior, unit testing specifically targets functional correctness at the component level. Other options relate to different testing methodologies or objectives, but unit testing distinctly aims to ensure that individual pieces of a program are functioning correctly.