Fred has been told he needs to test a component of the new content management application under development to validate its data structure, logic, and boundary conditions. What type of testing should he carry out?

A.
Acceptance testing

B.
Regression testing

C.
Integration testing

D.
Unit testing

Explanation:
D: Unit testing involves testing an individual component in a controlled environment to validate data structure, logic, and boundary conditions. After a programmer develops a
component, it is tested with several different input values and in many different situations. Unit testing can start early in development and usually continues throughout the development
phase. One of the benefits of unit testing is finding problems early in the development cycle, when it is easier and less expensive to make changes to individual units.
A is incorrect because acceptance testing is carried out to ensure that the code meets customer requirements. This testing is for part or all of the application, but not commonly one
individual component.
B is incorrect because regression testing refers to the retesting of a system after a change has taken place to ensure its functionality, performance, and protection. Essentially,
regression testing is done to identify bugs that have caused functionality to stop working as intended as a result of program changes. It is not unusual for developers to fix one problem,
only to inadvertently create a new problem, or for the new fix to break a fix to an old problem. Regression testing may include checking previously fixed bugs to make sure they have
not re-emerged and rerunning previous tests.
C is incorrect because integration testing involves verifying that components work together as outlined in design specifications. After unit testing, the individual components or units
are combined and tested together to verify that they meet functional, performance, and reliability requirements.