Even though unit testing can and should cover the major part of the application, there is still a need to work on functional and acceptance tests. Unlike unit tests, they provide higher-level verifications, and are usually performed at entry points, and rely heavily on user interface. At the end, we are creating applications that are, in most cases, used by humans, so being confident of our application's behavior is very important. This comfort status can be achieved by testing what the application is expected to do, from the point of view of real users.

Here, we'll try to provide an overview of functional and acceptance testing through a user interface. We'll use the Web as an example, even though there are many other types of user interfaces such as desktop applications, smart phone interfaces, and so on.