Mocking frameworks
Our project looks cool, but it's too simple and it is far from being a real project. It still doesn't use external resources. A database is required by Java projects so we'll try to introduce it, as well.
What is the common way to test code that uses external resources or third-party libraries? Mocks are the answer. A mock object, or simply a mock, is a simulated object that can be used to replace real ones. They are very useful when objects that depend on external resources are deprived of them.
In fact, you don't need a database at all while you are developing the application. Instead, you can use mocks to speed up development and testing and use a real database connection only at runtime. Instead of spending time setting up a database and preparing test data, we can focus on writing classes and think about them later on during integration time.
For demonstration purposes, we'll introduce two new classes: the Person class and the FriendCollection class that are designed...