What testing focuses on the internal workings of a software application?

White-box testing, also known as clear box testing, glass box testing, or structural testing, focuses on the internal workings of a software application. This type of testing involves looking at the code, algorithms, and logic within the application to ensure that it operates as intended. Testers performing white-box testing have knowledge of the internal code structure and can evaluate how the components work together. This allows them to design test cases based on program logic, covering paths, branches, loops, and conditions within the code.

In contrast, black-box testing examines the functionality of the application without any knowledge of the internal mechanics, emphasizing testing outputs based on given inputs without considering how those results are produced. Integration testing focuses on assessing the interactions between various components or systems, while system testing evaluates the complete and integrated software product against specified requirements. Each of these other testing types offers valuable insights but does not delve into the internal workings like white-box testing does.