How to write a unit test for a Spring Boot Controller endpoint

Question

I have a sample Spring Boot app with the following   Boot main class   SpringBootApplication public class DemoApplication        public static void main String   args            SpringApplication run DemoApplication class  args           Controller   RestController  EnableAutoConfiguration public class HelloWorld        RequestMapping          String gethelloWorld             return  Hello World               What s the easiest way to write a unit test for the controller  I tried the following but it complains about failing to autowire 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

User · Answer

Adding  WebAppConfiguration  org springframework test context web WebAppConfiguration  annotation to your DemoApplicationTests class will work

User · Answer

Let assume i am having a RestController with GET POST PUT DELETE operations and i have to write unit test using spring boot I will just share code of RestController class and respective unit test Wont be sharing any other related code to the controller  can have assumption on that     RestController  RequestMapping value       myapi myApp      produces     application json    public class AppController          Autowired     private AppService service        GetMapping     public MyAppResponse lt AppEntity gt  get   throws Exception            MyAppResponse lt AppEntity gt  response   new MyAppResponse lt AppEntity gt             service getApp   stream   forEach x - gt  response addData x                return response               PostMapping     public ResponseEntity lt HttpStatus gt  create  RequestBody AppRequest request  throws Exception             Validation code                service createApp request            return ResponseEntity ok HttpStatus OK               PutMapping     public ResponseEntity lt HttpStatus gt  update  RequestBody IDMSRequest request  throws Exception              Validation code         service updateApp request            return ResponseEntity ok HttpStatus OK               DeleteMapping     public ResponseEntity lt HttpStatus gt  delete  RequestBody AppRequest request  throws Exception              Validation                 service deleteApp request id            return ResponseEntity ok HttpStatus OK              RunWith SpringJUnit4ClassRunner class   SpringBootTest classes   Main class   WebAppConfiguration public abstract class BaseTest      protected MockMvc mvc      Autowired    WebApplicationContext webApplicationContext      protected void setUp           mvc   MockMvcBuilders webAppContextSetup webApplicationContext  build            protected String mapToJson Object obj  throws JsonProcessingException         ObjectMapper objectMapper   new ObjectMapper          return objectMapper writeValueAsString obj           protected  lt T gt  T mapFromJson String json  Class lt T gt  clazz        throws JsonParseException  JsonMappingException  IOException          ObjectMapper objectMapper   new ObjectMapper          return objectMapper readValue json  clazz           public class AppControllerTest extends BaseTest         MockBean     private IIdmsService service       private static final String URI     myapi myApp         Override     Before    public void setUp           super setUp              Test    public void testGet   throws Exception          AppEntity entity   new AppEntity          List lt AppEntity gt  dataList   new ArrayList lt AppEntity gt           AppResponse lt AppEntity gt  dataResponse   new AppResponse lt AppEntity gt           entity setId 1         entity setCreated at  2020-02-21 17 01 38 717863          entity setCreated by    Abhinav Kr            entity setModified at  2020-02-24 17 01 38 717863          entity setModified by    Jyoti                  dataList add entity          dataResponse setData dataList          Mockito when service getApp    thenReturn dataList          RequestBuilder requestBuilder    MockMvcRequestBuilders get URI                    accept MediaType APPLICATION JSON            MvcResult mvcResult   mvc perform requestBuilder  andReturn            MockHttpServletResponse response   mvcResult getResponse             String expectedJson   this mapToJson dataResponse           String outputInJson   mvcResult getResponse   getContentAsString             assertEquals HttpStatus OK value    response getStatus             assertEquals expectedJson  outputInJson             Test    public void testCreate   throws Exception           AppRequest request   new AppRequest           request createdBy   1         request AppFullName      My App            request appTimezone      India             String inputInJson   this mapToJson request          Mockito doNothing   when service  createApp Mockito any AppRequest class           service createApp request          Mockito verify service  Mockito times 1   createApp request           RequestBuilder requestBuilder    MockMvcRequestBuilders post URI                                                                accept MediaType APPLICATION JSON  content inputInJson                                                                contentType MediaType APPLICATION JSON           MvcResult mvcResult   mvc perform requestBuilder  andReturn           MockHttpServletResponse response   mvcResult getResponse           assertEquals HttpStatus OK value    response getStatus                Test    public void testUpdate   throws Exception           AppRequest request   new AppRequest           request id   1         request modifiedBy   1          request AppFullName      My App            request appTimezone      Bharat             String inputInJson   this mapToJson request          Mockito doNothing   when service  updateApp Mockito any AppRequest class           service updateApp request          Mockito verify service  Mockito times 1   updateApp request           RequestBuilder requestBuilder    MockMvcRequestBuilders put URI                                                                accept MediaType APPLICATION JSON  content inputInJson                                                                contentType MediaType APPLICATION JSON           MvcResult mvcResult   mvc perform requestBuilder  andReturn           MockHttpServletResponse response   mvcResult getResponse           assertEquals HttpStatus OK value    response getStatus                Test    public void testDelete   throws Exception           AppRequest request   new AppRequest           request id   1          String inputInJson   this mapToJson request          Mockito doNothing   when service  deleteApp Mockito any Integer class           service deleteApp request id          Mockito verify service  Mockito times 1   deleteApp request id           RequestBuilder requestBuilder    MockMvcRequestBuilders delete URI                                                                accept MediaType APPLICATION JSON  content inputInJson                                                                contentType MediaType APPLICATION JSON           MvcResult mvcResult   mvc perform requestBuilder  andReturn           MockHttpServletResponse response   mvcResult getResponse           assertEquals HttpStatus OK value    response getStatus

User · Answer

Here is another answer using Spring MVC s standaloneSetup  Using this way you can either autowire the controller class or Mock it       import static org mockito Mockito mock      import static org springframework test web server request MockMvcRequestBuilders get      import static org springframework test web server result MockMvcResultMatchers content      import static org springframework test web server result MockMvcResultMatchers status       import org junit Before      import org junit Test      import org junit runner RunWith      import org springframework beans factory annotation Autowired      import org springframework boot test context SpringBootTest      import org springframework http MediaType      import org springframework test context junit4 SpringJUnit4ClassRunner      import org springframework test web server MockMvc      import org springframework test web server setup MockMvcBuilders         RunWith SpringJUnit4ClassRunner class       SpringBootTest webEnvironment   SpringBootTest WebEnvironment RANDOM PORT      public class DemoApplicationTests            final String BASE URL    http   localhost 8080              Autowired         private HelloWorld controllerToTest           private MockMvc mockMvc            Before         public void setup                 this mockMvc   MockMvcBuilders standaloneSetup controllerToTest  build                        Test         public void testSayHelloWorld   throws Exception                Mocking Controller             controllerToTest   mock HelloWorld class                 this mockMvc perform get                            accept MediaType parseMediaType  application json charset UTF-8                           andExpect status   isOk                          andExpect content   mimeType MediaType APPLICATION JSON                        Test         public void contextLoads

User · Answer

The new testing improvements that debuted in Spring Boot 1 4 M2 can help reduce the amount of code you need to write situation such as these   The test would look like so   import static org springframework test web servlet request MockMvcRequestB  uilders get   import static org springframework test web servlet result MockMvcResultMat  chers content   import static org springframework test web servlet result MockMvcResultMat  chers status        RunWith SpringRunner class       WebMvcTest HelloWorld class      public class UserVehicleControllerTests             Autowired         private MockMvc mockMvc            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                         See this blog post for more details as well as the documentation

User · Answer

Spring MVC offers a standaloneSetup that supports testing relatively simple controllers  without the need of context       Build a MockMvc by registering one or more  Controller s instances and   configuring Spring MVC infrastructure programmatically  This allows   full control over the instantiation and initialization of controllers    and their dependencies  similar to plain unit tests while also making   it possible to test one controller at a time    An example test for your controller can be something as simple as   public class DemoApplicationTests        private MockMvc mockMvc        Before     public void setup             this mockMvc   standaloneSetup new HelloWorld    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

[java] How to write a unit test for a Spring Boot Controller endpoint

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