Stubbing void methods so that they throw exceptions

In this recipe, we will stub a void method that doesn't return a value, so it throws an exception.

Getting ready

For this recipe, our system under test will be a PersonProcessor class that, for simplicity, does only one thing: it delegates the process of saving person to the PersonSaver class. As shown in the following code, in case of success, true is returned; otherwise, false is returned:

public class PersonProcessor {

    private final PersonSaver personSaver;

    public PersonProcessor(PersonSaver personSaver) {
        this.personSaver = personSaver;
    }

    public boolean process(Person person) {
        try {
            personSaver.savePerson(person);
            return true;
        } catch (FailedToSavedPersonDataException e) {
            System.err.printf("Exception occurred while trying save person data [%s]%n", e);
            return false;
        }
    }

}

How to do it...

If you want your void method to throw an exception...