How to check JSON in response body with mockMvc

This is my method inside my controller which is annotated by @Controller

@RequestMapping(value = "/getServerAlertFilters/{serverName}/", produces = "application/json; charset=utf-8")
	@ResponseBody
	public JSONObject getServerAlertFilters(@PathVariable String serverName) {
		JSONObject json = new JSONObject();
		List<FilterVO> filteredAlerts = alertFilterService.getAlertFilters(serverName, "");
		JSONArray jsonArray = new JSONArray();
		jsonArray.addAll(filteredAlerts);
		json.put(SelfServiceConstants.DATA, jsonArray);
		return json;
	}

I am expecting {"data":[{"useRegEx":"false","hosts":"v2v2v2"}]} as my json.

And this is my JUnit test:

@Test
	public final void testAlertFilterView() {		
		try {			
			MvcResult result = this.mockMvc.perform(get("/getServerAlertFilters/v2v2v2/").session(session)
					.accept("application/json"))
					.andDo(print()).andReturn();
			String content = result.getResponse().getContentAsString();
			LOG.info(content);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

Here is the console output:

MockHttpServletResponse:
              Status = 406
       Error message = null
             Headers = {}
        Content type = null
                Body = 
       Forwarded URL = null
      Redirected URL = null
             Cookies = []

Even result.getResponse().getContentAsString() is an empty string.

Can someone please suggest how to get my JSON in my JUnit test method so that I can complete my test case.

I use TestNG for my unit testing. But in Spring Test Framework they both looks similar. So I believe your test be like below

@Test
public void testAlertFilterView() throws Exception {
    this.mockMvc.perform(get("/getServerAlertFilters/v2v2v2/").
            .andExpect(status().isOk())
            .andExpect(content().json("{'data':[{'useRegEx':'false','hosts':'v2v2v2'}]}"));
    }

If you want check check json Key and value you can use jsonpath .andExpect(jsonPath("$.yourKeyValue", is("WhatYouExpect")));

You might find thatcontent().json() are not solveble please add

import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

The 406 Not Acceptable status code means that Spring couldn't convert the object to json. You can either make your controller method return a String and do return json.toString(); or configure your own HandlerMethodReturnValueHandler. Check this similar question https://stackoverflow.com/questions/19204048/returning-jsonobject-using-responsebody-in-springmvc

You can try the below for get and post methods

@Autowired
private MuffinRepository muffinRepository;

@Test
public void testGetMethod throws Exception(){
	Muffin muffin = new Muffin("Butterscotch");
	muffin.setId(1L);
	
	BddMockito.given(muffinRepository.findOne(1L)).
		willReturn(muffin);
		
	mockMvc.perform(MockMvcRequestBuilders.
		get("/muffins/1")).
		andExpect(MockMvcResutMatchers.status().isOk()).
		andExpect(MockMvcResutMatchers.content().string("{\"id\":1, "flavor":"Butterscotch"}"));	
}

//Test to do post operation
@Test
public void testPostMethod throws Exception(){
	Muffin muffin = new Muffin("Butterscotch");
	muffin.setId(1L);
	
	BddMockito.given(muffinRepository.findOne(1L)).
		willReturn(muffin);
		
	mockMvc.perform(MockMvcRequestBuilders.
		post("/muffins")
		.content(convertObjectToJsonString(muffin))
		.contentType(MediaType.APPLICATION_JSON)
		.accept(MediaType.APPLICATION_JSON))
		.andExpect(MockMvcResutMatchers.status().isCreated())
		.andExpect(MockMvcResutMatchers.content().json(convertObjectToJsonString(muffin)));	
}

If the response is empty then make sure to override equals() and hashCode() methods on the Entity your repository is working with:

//Converts Object to Json String
private String convertObjectToJsonString(Muffin muffin) throws JsonProcessingException{
	ObjectWriter writer = new ObjectWriter().writer().withDefaultPrettyPrinter();
	return writer.writeValueAsString(muffin);
}

There are 2 ways to check JSON responses. Lemme guide you through both of them, (taking test method from the question above, and assuming response {"data":[{"useRegEx":"false","hosts":"v2v2v2"}]} as given above)

Method 1) Asserting complete JSON

@Test
public final void testAlertFilterView() {       
    mockMvc.perform(get("/getServerAlertFilters/v2v2v2/")
           .contentType("application/json"))
           .andExpect(status().isOk())
           // you may even read bigger json responses from file and convert it to string, instead of simply hardcoding it in test class
           .andExpect(content().json("{"data":[{"useRegEx":"false","hosts":"v2v2v2"}]}"))     
}

Method 2) Asserting specific key-value of response (not writing redundant piece of code)

.andExpect(jsonPath("$.data[0].useRegEx").value(false))
.andExpect(jsonPath("$.data[0].hosts").value("v2v2v2"));

Another thing you might need is the import statement,

import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;

If you want to check a few values in a specific field of JSON

.andExpect(MockMvcResultMatchers.jsonPath("$.message",
	AllOf.allOf(
		StringContains.containsString("name: must not be null"),
		StringContains.containsString("type: must not be null")
	)));

How it looks in the test class. JUnit4.

import com.fasterxml.jackson.databind.ObjectMapper;
import org.hamcrest.core.AllOf;
import org.hamcrest.core.StringContains;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;
import org.springframework.data.web.PageableHandlerMethodArgumentResolver;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.result.MockMvcResultMatchers;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;

@RunWith(MockitoJUnitRunner.class)
public class YourControllerTest {

  @Mock
  private YourService service;

  private MockMvc mvc;

  @Before
  public void setUp() {
    MockitoAnnotations.initMocks(this);
    mvc = MockMvcBuilders
        .standaloneSetup(new YourController(service))
        .setControllerAdvice(new YourExceptionHandler())
        .setCustomArgumentResolvers(new PageableHandlerMethodArgumentResolver())
        .build();
  }

  @Test
  public void yourControllerMethodName_400_validation() throws Exception {
    String path = "/orders/{orderId}/items";
    Integer orderId = 123;

    YourRequestDto requestDto = YourTestFactory.buildYourRequestDto();
    requestDto.setName(null);
    requestDto.setType(null);

    YourResponseDto expected = YourTestFactory.buildYourResponseDto(requestDto);

    Mockito
        .when(service.someMethod(orderId, requestDto))
        .thenReturn(expected);

    mvc
        .perform(
            MockMvcRequestBuilders.post(path, orderId)
                .contentType(MediaType.APPLICATION_JSON)
                .content(new ObjectMapper().writeValueAsString(requestDto))
        )
        .andExpect(MockMvcResultMatchers.status().isBadRequest())
        .andExpect(MockMvcResultMatchers.jsonPath("$.message",
            AllOf.allOf(
                StringContains.containsString("name: must not be null"),
                StringContains.containsString("type: must not be null")
            )));
  }
}