如何用JUnit Mock测试Controller与Service层的新增记录方法？

我想给Service层和Repository中新增数据库记录的方法编写Mock单元测试，但不知道正确操作方式，还遇到了报错。

现有代码 #

Controller代码 #

@PostMapping("/altaDiaInhabil")
private void addWorkingDay(@RequestBody CatDiaEntity day) throws Exception {
    try {
        catDiaInhabilService.addNewWorkingDay(day);
    } catch (Exception e) {
        LOGGER.error("Error in CatDiaEntity Values ");
        throw e;
    }
}

ServiceImpl代码 #

@Transactional
@Override
public void addNewWorkingDay(CatDiaEntity dayOff) throws Exception {
    try {
        catDiaRepository.saveWorkingDay(dayOff.getFechaInb(), dayOff.getDescDiaInb(),
                dayOff.getInhaMx(), dayOff.getInhabCh());

    } catch (Exception e) {
        LOGGER.error("An error ocurred to insert CatDiaEntity Data");

    }
}

遇到的报错 #

The method when in the type Mockito is not applicable for the arguments void

我编写的测试代码 #

@Mock
private CatDiaRepository catDiaRepository;

@InjectMocks
private CatDiaServiceImpl serviceImpl;

@BeforeEach
public void init() {
    MockitoAnnotations.openMocks(this);
    catDiEnatity = new CatDiaEntity();

}
@Test
public void testAddNewRecord() {
    catDiEnatity.setFechaInb("12/12/24");
    catDiEnatity.setDescDiaInb("New day");
    catDiEnatity.setInhaMx("1");
    catDiEnatity.setInhabCh("0");
    
    Mockito.when(catDiaRepository.saveWorkingDay(catDiEnatity.getFechaInb(), catDiEnatity.getDescDiaInb(), 
            catDiEnatity.getInhaMx(), catDiEnatity.getInhabCh())).thenReturn();
}

请问如何正确测试这两个方法？

一、Service层单元测试（解决报错） #

报错原因是saveWorkingDay是**无返回值（void）**方法，Mockito的when()只适用于有返回值的方法。针对void方法，需改用doNothing()或doThrow()来模拟行为：

正确的Service测试代码 #

@Mock
private CatDiaRepository catDiaRepository;

@InjectMocks
private CatDiaServiceImpl serviceImpl;

private CatDiaEntity catDiaEntity;

@BeforeEach
public void init() {
    MockitoAnnotations.openMocks(this);
    catDiaEntity = new CatDiaEntity();
}

@Test
public void testAddNewRecord_Success() throws Exception {
    // 准备测试数据
    catDiaEntity.setFechaInb("12/12/24");
    catDiaEntity.setDescDiaInb("New day");
    catDiaEntity.setInhaMx("1");
    catDiaEntity.setInhabCh("0");

    // 模拟Repository的void方法正常执行
    Mockito.doNothing().when(catDiaRepository)
            .saveWorkingDay(catDiaEntity.getFechaInb(), catDiaEntity.getDescDiaInb(),
                    catDiaEntity.getInhaMx(), catDiaEntity.getInhabCh());

    // 调用Service方法
    serviceImpl.addNewWorkingDay(catDiaEntity);

    // 验证Repository方法是否按预期调用
    Mockito.verify(catDiaRepository, Mockito.times(1))
            .saveWorkingDay("12/12/24", "New day", "1", "0");
}

// 可选：测试异常场景
@Test
public void testAddNewRecord_Exception() throws Exception {
    catDiaEntity.setFechaInb("12/12/24");
    // 模拟Repository抛出异常
    Mockito.doThrow(new RuntimeException("DB error")).when(catDiaRepository)
            .saveWorkingDay(anyString(), anyString(), anyString(), anyString());

    // 调用Service方法（内部会捕获异常）
    serviceImpl.addNewWorkingDay(catDiaEntity);

    // 验证Repository方法被调用
    Mockito.verify(catDiaRepository, Mockito.times(1))
            .saveWorkingDay("12/12/24", null, null, null);
}

核心说明：

• doNothing()：模拟void方法正常执行，无额外操作
• verify()：验证Mock对象的方法调用次数、参数匹配情况，这是void方法测试的核心验证逻辑
• anyString()是Mockito参数匹配器，用于模糊匹配参数

二、Controller层单元测试 #

Controller层测试需用MockMvc模拟HTTP请求，同时Mock依赖的Service层：

Controller测试代码示例 #

@WebMvcTest(CatDiaController.class)
public class CatDiaControllerTest {

    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private CatDiaInhabilService catDiaInhabilService;

    @Test
    public void testAddWorkingDay_Success() throws Exception {
        // 准备请求体数据
        CatDiaEntity requestBody = new CatDiaEntity();
        requestBody.setFechaInb("12/12/24");
        requestBody.setDescDiaInb("New day");
        requestBody.setInhaMx("1");
        requestBody.setInhabCh("0");

        // 模拟Service方法无异常执行
        Mockito.doNothing().when(catDiaInhabilService).addNewWorkingDay(requestBody);

        // 发送POST请求并验证响应
        mockMvc.perform(MockMvcRequestBuilders.post("/altaDiaInhabil")
                        .contentType(MediaType.APPLICATION_JSON)
                        .content(new ObjectMapper().writeValueAsString(requestBody)))
                .andExpect(MockMvcResultMatchers.status().isOk());

        // 验证Service方法被调用
        Mockito.verify(catDiaInhabilService, Mockito.times(1)).addNewWorkingDay(requestBody);
    }

    @Test
    public void testAddWorkingDay_Exception() throws Exception {
        CatDiaEntity requestBody = new CatDiaEntity();
        // 模拟Service抛出异常
        Mockito.doThrow(new Exception("Invalid data")).when(catDiaInhabilService).addNewWorkingDay(any(CatDiaEntity.class));

        // 发送请求并验证异常响应
        mockMvc.perform(MockMvcRequestBuilders.post("/altaDiaInhabil")
                        .contentType(MediaType.APPLICATION_JSON)
                        .content(new ObjectMapper().writeValueAsString(requestBody)))
                .andExpect(MockMvcResultMatchers.status().isInternalServerError());

        // 验证Service方法被调用
        Mockito.verify(catDiaInhabilService, Mockito.times(1)).addNewWorkingDay(requestBody);
    }
}

核心说明：

• @WebMvcTest：专门用于Controller层测试，自动配置MockMvc
• @MockBean：Mock Controller依赖的Service对象
• MockMvc：模拟HTTP请求，验证响应状态、内容等

内容的提问来源于stack exchange，提问作者Root93