spring boot 单元测试使用new MockMvc和@RunWith+@AutoConfigureMockMvc注解的区别

在单元测试中用以上两种都能实现，但是@RunWith注解还可以实现代码中的依赖注入(前者不能)

单测代码如下

Slf4j
@RestController
@RequestMapping("/rest")
public class ArticleRestController {

    @Resource
    ArticleRestService articleRestService;

    /**
     * 增加一篇文章
     *
     * @param article
     * @return
     */
    // @RequestMapping(value = "/article", method = RequestMethod.POST, produces = "application/json")
    @PostMapping("/article")
    public AjaxResponse saveArticle(@RequestBody Article article) {
        articleRestService.saveArticle(article);
        return AjaxResponse.success(article);
    }
}

自定义MockMvc做法，会报出空指针异常

@Slf4j
@SpringBootTest
public class ArticleRestControllerTest {

    //mock对象
    private MockMvc mockMvc;

    //mock对象初始化
    @BeforeEach
    public void setUp() {
        mockMvc = MockMvcBuilders.standaloneSetup(new ArticleRestController()).build();
    }

    //测试方法
    @Test
    public void saveArticle() throws Exception {

        String article = "{
" +
                "    "id": 1,
" +
                "    "author": "zimug",
" +
                "    "title": "手摸手教你开发spring boot",
" +
                "    "content": "c",
" +
                "    "reader":[{"name":"zimug","age":18},{"name":"kobe","age":37}]
" +
                "}";
        MvcResult result = mockMvc.perform(
                MockMvcRequestBuilders.request(HttpMethod.POST, "/rest/article")
                .contentType("application/json").content(article))
                .andExpect(MockMvcResultMatchers.status().isOk())
                .andExpect(MockMvcResultMatchers.jsonPath("$.data.author").value("zimug"))
                .andExpect(MockMvcResultMatchers.jsonPath("$.data.reader[0].age").value(18))
                .andDo(print())
                .andReturn();

        log.info(result.getResponse().getContentAsString());

    }
}

使用@RunWith(SpringRunner.class)注解

@Slf4j
@RunWith(SpringRunner.class)
@AutoConfigureMockMvc   //相当于new MockMvc
@SpringBootTest
public class ArticleRestControllerTest2 {

    //mock对象
    @Resource
    private MockMvc mockMvc;

    @Resource
    ArticleRestService articleRestService;

    //测试方法
    @Test
    public void saveArticle() throws Exception {

        String article = "{
" +
                "    "id": 1,
" +
                "    "author": "zimug",
" +
                "    "title": "手摸手教你开发spring boot",
" +
                "    "content": "c",
" +
                "    "reader":[{"name":"zimug","age":18},{"name":"kobe","age":37}]
" +
                "}";
        MvcResult result = mockMvc.perform(
                MockMvcRequestBuilders.request(HttpMethod.POST, "/rest/article")
                .contentType("application/json").content(article))
                .andExpect(MockMvcResultMatchers.status().isOk())
                .andExpect(MockMvcResultMatchers.jsonPath("$.data.author").value("zimug"))
                .andExpect(MockMvcResultMatchers.jsonPath("$.data.reader[0].age").value(18))
                .andDo(print())
                .andReturn();

        log.info(result.getResponse().getContentAsString());

    }
}

不会报出异常

解析

• RunWith方法为我们构造了一个的Servlet容器运行运行环境，并在此环境下测试。然而为什么要构建servlet容器？因为使用了依赖注入，注入了MockMvc对象，而在上一个例子里面是我们自己new的。
• 而@AutoConfigureMockMvc注解，该注解表示 MockMvc由spring容器构建，你只负责注入之后用就可以了。这种写法是为了让测试在Spring容器环境下执行。
• Spring的容器环境是什么呢？比如常见的 Service、Dao 都是Spring容器里的bean，装载到容器里面都可以使用@Resource和@Autowired来注入引用。
• 简单的说：如果你单元测试代码使用了依赖注入就加上@RunWith，如果你不是手动new MockMvc对象就加上@AutoConfigureMockMvc