A systems administrator is working with a developer to upgrade to the latest version of Java, but first, the sysadmin wants to see whether changes in code have caused previously existing functionality to fail. What is this called?

The scenario described involves a systems administrator assessing whether changes made in the codebase, such as an upgrade to the latest version of Java, have led to the failure of previously functioning features. This process is referred to as regression testing.

Regression testing is specifically designed to ensure that recent code changes do not adversely affect the existing functionalities of the software. It aims to verify that the new changes perform as intended while maintaining the integrity of previously developed features. This is essential after any updates or enhancements, as it helps to identify any unintended side effects of the new code.

In contrast, unit testing focuses on individual components of the code to ensure they work correctly in isolation, while integration testing examines the interaction between combined software modules to confirm they work together as expected. Solution design refers to the planning and outlining of an architectural framework for the intended software application, not an evaluation after code changes. Hence, regression testing is the appropriate practice in this context, confirming that the existing functionalities remain intact despite the changes.