What does 'regression testing' determine?

Regression testing is primarily focused on ensuring that recent code changes do not negatively impact the existing functionality of the software. When developers implement modifications—whether that involves fixing bugs, adding new features, or improving performance—there is always the risk that these changes might inadvertently disrupt previously working aspects of the application.

The goal of regression testing is to identify these potential issues by running a suite of tests that verify that the existing functions behave as expected after the changes have been made. This helps maintain software stability and reliability over time.

While improving user experience, evaluating performance metrics, and assessing new feature functionality are important aspects of software development, they are not the primary focus of regression testing. Instead, regression testing is specifically concerned with safeguarding the integrity of what is already there against changes that may affect it.