How to use dummy values in Junit when values from database are required

[Laryssa Fernandes]

I have to write Junit test cases for some code. This code uses a database that I don't have. I have to write test cases for methods that call methods from other classes that access the database. Is it possible for me to somehow cause the methods in the other classes to return some dummy values when values from the database are required? Without changing any of the code...

[Hebert Coelho]

Create a class that extends your database class, pass it in the constructor.

Somethig like this:

public class CarDAO{
     // real class that goes to the database
    public Car find(int carId){
        return entityManager.find(Car.class, carId);
    }
}

public class CarDAOTest extends CarDAO{
     // fake class
    public Car find(int carId){
        return new Car();
    }
}

public class CarFacade{
    public CarFacade (CarDAO carDAO){
        this.carDAO = carDAO;
    }
}

//in your test
public class CarTest{
    private CarFacade carFacade  = new CarFacade(new CarDAOTest);
// do your tests
}

You also could use JUnit with HSQLDB that will works as a fake database: JUnit with HSQLDB, JPA and Hibernate.