What is white-box testing primarily focused on?

White-box testing is primarily focused on utilizing internal knowledge of the software to guide the testing process. This type of testing involves having access to the code, architecture, and internal workings of the application. The tester leverages this comprehensive understanding to create effective test cases based on the code structure, logic, and paths.

By knowing how the software is structured, testers can ensure that they cover all possible branches and paths in the code, leading to a thorough examination of functionality and identification of potential vulnerabilities. This approach is in contrast to black-box testing, which does not take into account the internal workings of the application and instead focuses solely on the external behavior and outputs.

While evaluating performance under extreme conditions, testing the external functionality, and conducting user acceptance tests are important aspects of software testing, they do not focus on the internal structure of the code like white-box testing does.