Java 如何在单元测试期间注入 PersistenceContext？
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How to inject PersistenceContext during unit testing?
提问by yegor256
This is my java class:
这是我的java类：
public class Finder {
@PersistenceContext(unitName = "abc")
EntityManager em;
public boolean exists(int i) {
return (this.em.find(Employee.class, i) != null);
}
}
This is the unit test:
这是单元测试：
public class FinderTest {
@Test public void testSimple() {
Finder f = new Finder();
assert(f.exists(1) == true);
}
}
Testing fails with NullPointerExceptionsince Finder.emis not injected by anyone. How should I handle this situation properly? Does there any best practice exist?
测试失败，NullPointerException因为Finder.em不是由任何人注入的。我应该如何正确处理这种情况？是否存在任何最佳实践？
采纳答案by Pascal Thivent
Without a container like Spring (or something like Unitils- which is Spring based), you will have to inject the entity manager manually. In that case, you coulduse something like this as base class:
如果没有像 Spring 这样的容器（或类似Unitils——它是基于 Spring 的），你将不得不手动注入实体管理器。在这种情况下，你可以使用这样的东西作为基类：
public abstract class JpaBaseRolledBackTestCase {
protected static EntityManagerFactory emf;
protected EntityManager em;
@BeforeClass
public static void createEntityManagerFactory() {
emf = Persistence.createEntityManagerFactory("PetstorePu");
}
@AfterClass
public static void closeEntityManagerFactory() {
emf.close();
}
@Before
public void beginTransaction() {
em = emf.createEntityManager();
em.getTransaction().begin();
}
@After
public void rollbackTransaction() {
if (em.getTransaction().isActive()) {
em.getTransaction().rollback();
}
if (em.isOpen()) {
em.close();
}
}
}
回答by Richard Kettelerij
It depends on whatyou want to test. When you have complex business logic in your Finderclass you may want to mock the EntityManager- using a mocking framework like EasyMockor Mockito- in order to unit test that logic.
这取决于你想测试什么。当您的类中有复杂的业务逻辑时，您Finder可能想要模拟EntityManager- 使用像EasyMock或Mockito这样的模拟框架- 以便对该逻辑进行单元测试。
Now since that's not the case I suspect you want to test the persistency of the Employeeentity (this is often referred to as integration testing). This requires the use of a database. To make testing easy and keep your tests portable you can use an in-memory database like HSQLDBfor this purpose. In order to start HSQLDB, create a persistence context and inject this context into your Finder class it's advisable to use an IoC framework like Spring.
现在，由于情况并非如此，我怀疑您想要测试Employee实体的持久性（这通常称为集成测试）。这需要使用数据库。为了简化测试并保持测试的可移植性，您可以为此使用内存数据库，如HSQLDB。为了启动 HSQLDB，创建一个持久化上下文并将这个上下文注入到您的 Finder 类中，建议使用 IoC 框架，如Spring。
There are tons of tutorials on the internet that explain how to use JPA/Spring/HSQLDB. Take a look at this example project: Integration testing with Maven 2, Spring 2.5, JPA, Hibernate, and HSQLDB
互联网上有大量教程解释如何使用 JPA/Spring/HSQLDB。看一下这个示例项目：Integration testing with Maven 2, Spring 2.5, JPA, Hibernate, and HSQLDB
回答by Ahmet Koylu
Create another package-private constructor and add only EntityManager then call the other constructor for default behavior.
创建另一个包私有构造函数并仅添加 EntityManager 然后调用另一个构造函数以获得默认行为。
@PersistentContext
private EntityManager entityManager;
private ManagementService managementService;
@Autowired
public SomeClass(ManagementService managementService) {
this.managementService = managementService;
}
SomeClass(ManagementService managementService, EntityManager entityManager) {
this(managementService);
this.entityManager = entityManager;
}
