我有一个带有以下内容的示例Spring Boot应用程序

引导主类

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

控制者

@RestController
@EnableAutoConfiguration
public class HelloWorld {
    @RequestMapping("/")
    String gethelloWorld() {
        return "Hello World!";
    }

}

为控制器编写单元测试的最简单方法是什么？我尝试了以下操作，但它抱怨无法自动连接WebApplicationContext

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = DemoApplication.class)
public class DemoApplicationTests {

    final String BASE_URL = "http://localhost:8080/";

    @Autowired
    private WebApplicationContext wac;

    private MockMvc mockMvc;

    @Before
    public void setup() {
        this.mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build();
    }

    @Test
    public void testSayHelloWorld() throws Exception{

         this.mockMvc.perform(get("/")
                 .accept(MediaType.parseMediaType("application/json;charset=UTF-8")))
                 .andExpect(status().isOk())
                 .andExpect(content().contentType("application/json"));
    }

    @Test
    public void contextLoads() {
    }

}