Guice - JUnit integration example

GuiceJUnitRunner.java

import com.google.inject.AbstractModule;
import com.google.inject.Guice;
import com.google.inject.Injector;
import org.junit.runners.BlockJUnit4ClassRunner;
import org.junit.runners.model.InitializationError;

public class GuiceJUnitRunner extends BlockJUnit4ClassRunner {

    public GuiceJUnitRunner(Class<?> klass) throws InitializationError {
        super(klass);
    }

    @Override
    protected Object createTest() throws Exception {
        final Object object = super.createTest();

        final Injector injector = Guice.createInjector(new AbstractModule() {
            @Override
            protected void configure() {
                bind(PersonDAO.class).to(PersonDAOImpl.class);
                bind(PersonSearch.class).to(PersonServiceImpl.class);
            }
        });
        injector.injectMembers(object);
        return object;
    }
}

Person.java

public class Person {

    private final Integer id;
    private final String name;

    public Person(Integer id, String name) {
        this.id = id;
        this.name = name;
    }

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return "Person{" + "name='" + name + '\'' +  '}';
    }
}

PersonDAO.java

import java.util.List;

public interface PersonDAO {

    List<Person> findAll();
}

PersonDAOImpl.java

import java.util.Arrays;
import java.util.List;

public class PersonDAOImpl implements PersonDAO {

    public List<Person> findAll() {

        return Arrays.asList(
                new Person(1, "John Doe"),
                new Person(2, "Joe Bloggs")
        );
    }

}

PersonSearch.java

import java.util.List;

public interface PersonSearch {

    List<Person> findAll();
}

PersonServiceImpl.java

import javax.inject.Inject;
import java.util.List;

public class PersonServiceImpl implements PersonSearch {

    private final PersonDAO personDAO;

    @Inject
    public PersonServiceImpl(PersonDAO personDAO) {
        this.personDAO = personDAO;
    }

    public List<Person> findAll() {

        return personDAO.findAll();
    }
}

PersonServiceTest.java

import org.junit.Test;
import org.junit.runner.RunWith;

import javax.inject.Inject;
import java.util.List;

import static org.junit.Assert.assertTrue;

@RunWith(GuiceJUnitRunner.class)
public class PersonServiceTest {

    @Inject private PersonSearch lookupSearch;

    @Test
    public void testSearch() {

        final List<Person> all = lookupSearch.findAll();
        assertTrue(all.size() == 2);
    }

}