What is the objective of a functionality test?

The objective of a functionality test is to ensure that the program meets the initial requirements set during the development process. This type of testing primarily focuses on verifying that the software behaves as expected and performs its intended functions correctly. During functionality testing, various aspects of the application are evaluated, such as specific features, user commands, data manipulation, and interaction with external systems, to confirm that all requirements are satisfied.

The other choices highlight important aspects of software evaluation but do not directly align with the primary goal of functionality testing. For example, efficiency of algorithms pertains to performance testing, measuring user interface responsiveness relates more to usability testing, and identifying security vulnerabilities is part of security testing. Each of these areas serves a different purpose in the software development lifecycle, but functionality testing specifically targets compliance with defined requirements.