在內存中使用derby的單元測試數據庫層DAO

Question

我想用此單元測試我的DAO實現：

public class BaseDAOImplTest {

    private EntityManagerFactory emFactory;
    private EntityManager em;
    private static Logger logger = Logger.getLogger(BaseDAOImplTest.class
            .getName());

    @Before
    public void setUp() throws SQLException, ClassNotFoundException {

        logger.info("Starting in-memory database for unit tests");

        try {

            //Creating testDB database
            Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
            DriverManager.getConnection("jdbc:derby:memory:TestingDB;create=true");
            logger.info("Building JPA EntityManager for unit tests");

            //Creating Entity Manager
            emFactory = Persistence.createEntityManagerFactory("TestingDB");
            em = emFactory.createEntityManager();
        } catch (ClassNotFoundException e) {

            e.printStackTrace();
        }
    }

    @Test
    public void testPersistExcursion() {
        BaseDAOImpl baseDao = new BaseDAOImpl(Excursion.class, em);
        Calendar c = Calendar.getInstance();
        c.set(2013, 8, 24);
        Excursion ex1 = createExcursion(c.getTime(), 10, "Simple excursion 1", "New York", 35);
        ex1 = baseDao.persist(ex1);
        assertEquals(baseDao.findById(ex1.getId()), ex1);
    }

    @Test
    public void testPersist() {
        try {
            Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
            String dbURL = "jdbc:derby:memory:TestingDB;create=true";
            Connection conn = getConnection(dbURL);
            EntityManagerFactory f = Persistence.createEntityManagerFactory("TestingDB");
            EntityManager em = f.createEntityManager();
            BaseDAOImpl b = new BaseDAOImpl(Excursion.class, em);
            Calendar c = Calendar.getInstance();
            c.set(2013, 8, 24);
            Excursion ex1 = createExcursion(c.getTime(), 10, "Simple excursion 1", "New York", 35);
            ex1 = b.persist(ex1);
            assertEquals(b.findById(ex1.getId()), ex1);
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(BaseDAOImplTest.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

testPersist正在工作，結果是該測​​試通過了。 但是在testPersistExcursion我遇到了NullPointerException錯誤，因為在setUp我得到了：

java.lang.ClassNotFoundException: org.apache.derby.jdbc.EmbeddedDriver

我只是想將EntityManager添加為全局對象並在setUp初始化，因此不需要在每個單元測試中都再次編寫這些行（我在某些文章中看到過，並且我認為這是一個很好的方法）。 但是，這有什么問題呢？ 為什么在單元測試工作，但在setUp我找不到驅動程序？ 謝謝

編輯：

我發現了問題，那是行家。 我有錯誤的artifactId。 但是現在我在這一行emFactory = Persistence.createEntityManagerFactory("TestingDB");了"Unable to build EntityManagerFactory"的問題： emFactory = Persistence.createEntityManagerFactory("TestingDB");

我的持久性單元：

<persistence-unit name="TestingDB" transaction-type="RESOURCE_LOCAL">
    <class>cz.infi.javatravelagency.entities.Reservation</class>
    <class>cz.infi.javatravelagency.entities.Trip</class>
    <class>cz.infi.javatravelagency.entities.Customer</class>
    <class>cz.infi.javatravelagency.entities.Excursion</class>
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    <properties>
      <property name="hibernate.connection.username" value="APP"/>
      <property name="hibernate.connection.driver" value="org.apache.derby.jdbc.EmbeddedDriver"/>
      <property name="hibernate.connection.password" value="APP"/>
      <property name="hibernate.connection.url" value="jdbc:derby:memory:TestingDB;create=true"/>
      <property name="hibernate.connection.autoReconnect" value="true" />  
      <property name="hibernate.connection.autoReconnectForPools" value="true" />  
      <property name="hibernate.dialect" value="org.hibernate.dialect.DerbyDialect" />  
    </properties>
  </persistence-unit>

Answer 1

好的，根據我的評論，我已經嘗試過此方法，並且它按預期工作。 運行測試時，將按預期獲取src / test / resources / META-INF中特定於測試的persistence.xml。

然后，您可以在以下幾行中創建一個BaseDao類：

public class BaseDao {

    private static EntityManagerFactory emf;

    public static EntityManager getEntityManager() {

        if (emf == null) {

            emf = Persistence.createEntityManagerFactory("test");
        }

        return emf.createEntityManager();
    }
}

}

一切都更好！