Java 用mockito对DAO层进行单元测试

我正在尝试使用Mockito对我的Spring+Hibernate项目进行单元测试。下面是我的DAO类的实现：

@Repository
public class EmployeeDAOImpl implements EmployeeDAO {
    @Autowired
    private SessionFactory sessionFactory;

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
        System.out.println("Session factory");
    }
    @Override
    public ArrayList<Employees> getAllData() {
        System.out.println("Inside get all data");
        Session session = sessionFactory.getCurrentSession();
        System.out.println("session created");
        Criteria cr = session.createCriteria(Employees.class, "employees").setResultTransformer(
                Criteria.DISTINCT_ROOT_ENTITY);

        return (ArrayList<Employees>) cr.list();
    }

}

堆栈跟踪：

java.lang.NullPointerException
    at com.assignment.dao.impl.EmployeeDAOImpl.getAllData(EmployeeDAOImpl.java:77)
    at com.assignment.DAOTest.EmployeeDAOImplTest.testGetAllData(EmployeeDAOImplTest.java:84)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

---

EmployeeDAOImpl

包含以下代码：

    Criteria cr = session.createCriteria(Employees.class, "employees").setResultTransformer(
            Criteria.DISTINCT_ROOT_ENTITY);

您的测试有：

    Mockito.doReturn(criteria).when(session)
            .createCriteria(ConceptModelDetails.class);

从您的代码中我可以看出，您正确地模拟了它正在返回的

sessionFactory

和

session

。但是，您没有正确模拟

session.createCriteria（Employee.class，“employees”）

（而是为

session.createCriteria（ConceptModelDetails.class）

）设置返回值）。因此，模拟的返回值将为

null

。因此，当您立即取消对它的引用时（调用

setResultTransformer

），您将得到一个

NullPointerException

---

要验证这一点，请尝试单步进入调试器，或将日志语句添加到

EmployeeDAOImpl

，这些语句显示

sessionFactory

、

session

的值以及来自

session的结果。createCriteria（…）

始终包含堆栈跟踪。（在这方面，考虑使用Spring数据而不是手工编写DAOS）为什么雇员是@间谍？为什么要在声明中实例化它？@ CuryIs完成了。请详细说明一下（使用Spring Data）。？上述堆栈跟踪与EmployeeDAOImpl或EmployeeDAOImplTest类没有任何共同之处，它指向ConceptModelDAOImpl和ConceptModelDAOImplTest

    Criteria cr = session.createCriteria(Employees.class, "employees").setResultTransformer(
            Criteria.DISTINCT_ROOT_ENTITY);

    Mockito.doReturn(criteria).when(session)
            .createCriteria(ConceptModelDetails.class);