Junit tests in Java (Spring, MVC) for DAO and Service

Question

I want to write a Junit test to the DAO. The project work itself. All classes and methods work. All data from the test correctly. Why is it bad?

Exception is --- Could not autowire field: private com.epam.edu.jtc.dao.CoursesDAOImpl com.epam.edu.jtc.test.CourseTest.coursesDao; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.epam.edu.jtc.dao.CoursesDAOImpl] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

 @RunWith(SpringJUnit4ClassRunner.class)
 @ContextConfiguration(locations={"classpath:test-context.xml" })

 public class CourseTest
 {
@Autowired
private CoursesDAOImpl coursesDao;

@Test
public void testFindCourseById()
{
    Course course = coursesDao.findCourseById(322);

    Assert.assertEquals("Python", course.getName());
    Assert.assertEquals("Development Manager", course.getCategory());
    Assert.assertEquals("python.com", course.getLinks());
    return;
}
}

test-context.xml

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xmlns:context="http://www.springframework.org/schema/context"
xmlns:security="http://www.springframework.org/schema/security"
xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/mvc  http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">

<!-- the test application context definition for the jdbc based tests -->

 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
    destroy-method="close"
    p:driverClassName="org.h2.Driver"
    p:url="jdbc:h2:tcp://localhost:9092/~/QWE;INIT=create schema if not exists QWE\;"
    p:username="sa"
    p:password=""
     />

CoursesDAO.java

  public interface CoursesDAO {

  public Course findCourseById(Integer key);
  }

CoursesDAOImpl.java

  @Repository
 public class CoursesDAOImpl implements CoursesDAO {

 @Autowired
 private SessionFactory sessionFactory;

 public Course findCourseById(Integer id) {

    Session session = sessionFactory.getCurrentSession();
    session.beginTransaction();
    Course course = (Course) session.get(Course.class, id);
    session.getTransaction().commit();

    return course;
   }

Answer 1

You should autowire the interface, instead of the implementation class, like so:

@Autowired
private CoursesDAO coursesDao;

Hope it helps.