Fake objects

Fake objects have real working implementations of the class they simulate. However, they usually do the same task in a much simpler way. Imagine a fake database class that uses an array list instead of a real database. This fake object is simpler to control than the real database. A common example in real life is to use a simpler database during testing.

In the Java world, developers like to use HSQLDB (HyperSQL database), an in-memory database that is much faster and easier to set up in the test code than a real database. We will talk more about in-memory databases when we discuss integration testing.