What type of testing assesses attributes unrelated to functionality, such as usability and reliability?

Non-functional testing is a category of testing that focuses on assessing various attributes of a system that are not related to specific functional requirements. This type of testing evaluates aspects such as usability, performance, reliability, security, and scalability.

Usability testing, for instance, examines how easy and intuitive the application is for end-users, while reliability testing investigates how consistently the application performs under expected conditions. Non-functional testing is crucial because it helps ensure that the software meets quality standards and user expectations regarding performance and other attributes that impact user experience.

In contrast, functional testing primarily verifies that the software performs its intended functions correctly, regression testing checks for new bugs in existing functionalities after changes to the code, and acceptance testing determines whether the software meets the acceptance criteria of the client or end-user, often focusing on functional requirements. These approaches do not specifically address the non-functional characteristics that are assessed in non-functional testing.