模型和单元测试——如何控制新对象的创建

Question

我有这个方法要进行单元测试:

public class DPService {
    public DPModel saveTreeRecursively(DPDTO dpDTO) {
        DPModel dpModel = new DPModel(dpDTO.getDPKey(), dpDTO.getName());
        DPModel savedDpModel = dpDAO.save(dpModel);
        Long dpId = savedDPModel.getDpId();
        // after some operations
        return savedDpModel;
    }
}

测试类是:

public class DPServiceTest {
    @Test
    public void testSaveTreeRecursively() {
        DPModel dpModel1 = new DPModel(dpKey, dpName); // same dpKey and dpName 
        //used in the SUT method to create DPModel, dpModel
        DPModel dpModel2 = new DPModel(dpKey, dpName);
        dpModel2.setDPId(123L);
        // SUT
        DPService dpService = new DPService();
        // creating a mock DAO so that, the unit testing is independent of real DAO
        DPDaoMock dpDaoMock = Mockito.mock(DPDao.class);
        // we want to control the mock dpDAO so that it returns 
        // the model we want that the below SUT method uses; basically we are pretending that
        // the dpDAO saved the dpModel1 with a primary key, dpId = 123
        // and returned the dpModel2 saved in the database.
        Mockito.when(dpDaoMock.save(dpModel1)).thenReturn(dpModel2);
        DPModel dpModel3 = dpService.saveTreeRecursively(dpDTO);
        assertEquals(dpModel3.getDpID(), 123L);
    }
}

显然SUT方法在

行失败了

Long dpId = savedDPModel.getDpId();

，因为在SUT方法中创建的实例与我们希望从dpDaoMock中使用的实例不同。

那么我该如何克服这个问题呢?有没有其他更好的模拟DAO的方法?

谢谢

Answer 1

一些选项

<标题>抽象工厂h1> DPModel的工厂接口可以作为DPService的依赖引入。这样，(工厂的)工厂方法的返回值就可以模拟并用于断言。

请参考抽象工厂模式。

<标题>匹配器h1> 拟匹配器可以用来检查模拟方法的参数:

Mockito.when(dpDaoMock.save(Matchers.any())).thenReturn(dpModel2);

或更严格的例子:

Mockito.when(dpDaoMock.save(Matchers.argThat(new ArgumentMatcher<DPModel>() {
    @Override
    public boolean matches(Object argument) {
        DPModel dpModel = (DPModel) argument;
        return dpModel.getDpId().equals(123L);
    }
}))).thenReturn(dpModel2);