Understanding the purpose of functional tests
In Chapter 18, Testing Your Code with Unit Test Cases and TDD, we discussed the advantages of automatic tests, how to design them, and their challenges. Functional tests use the same techniques and tools as unit and integration tests but differ from them in that they are run only at the end of each sprint. They have the fundamental role of verifying that the current version of the whole software complies with its specifications.
Since functional tests also involve the user interface (UI), they need further tools to simulate, somehow, the way the user acts in the UI. We will discuss this point further throughout the chapter. The need for extra tools is not the only challenge the UI brings with it, because UIs also see frequent and major changes. Thus, we mustn't design tests that depend on the UI's graphical details or we might be forced to completely rewrite all the tests at each UI change. That's why it is sometimes...