Using Spring MVC Test to unit test multipart POST request

Question

Since MockMvcRequestBuilders#fileUpload is deprecated, you'll want to use MockMvcRequestBuilders#multipart(String, Object...) which returns a MockMultipartHttpServletRequestBuilder. Then chain a bunch of file(MockMultipartFile) calls.

Here's a working example. Given a @Controller

@Controller
public class NewController {

    @RequestMapping(value = "/upload", method = RequestMethod.POST)
    @ResponseBody
    public String saveAuto(
            @RequestPart(value = "json") JsonPojo pojo,
            @RequestParam(value = "some-random") String random,
            @RequestParam(value = "data", required = false) List<MultipartFile> files) {
        System.out.println(random);
        System.out.println(pojo.getJson());
        for (MultipartFile file : files) {
            System.out.println(file.getOriginalFilename());
        }
        return "success";
    }

    static class JsonPojo {
        private String json;

        public String getJson() {
            return json;
        }

        public void setJson(String json) {
            this.json = json;
        }

    }
}

and a unit test

@WebAppConfiguration
@ContextConfiguration(classes = WebConfig.class)
@RunWith(SpringJUnit4ClassRunner.class)
public class Example {

    @Autowired
    private WebApplicationContext webApplicationContext;

    @Test
    public void test() throws Exception {

        MockMultipartFile firstFile = new MockMultipartFile("data", "filename.txt", "text/plain", "some xml".getBytes());
        MockMultipartFile secondFile = new MockMultipartFile("data", "other-file-name.data", "text/plain", "some other type".getBytes());
        MockMultipartFile jsonFile = new MockMultipartFile("json", "", "application/json", "{\"json\": \"someValue\"}".getBytes());

        MockMvc mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).build();
        mockMvc.perform(MockMvcRequestBuilders.multipart("/upload")
                        .file(firstFile)
                        .file(secondFile)
                        .file(jsonFile)
                        .param("some-random", "4"))
                    .andExpect(status().is(200))
                    .andExpect(content().string("success"));
    }
}

And the @Configuration class

@Configuration
@ComponentScan({ "test.controllers" })
@EnableWebMvc
public class WebConfig extends WebMvcConfigurationSupport {
    @Bean
    public MultipartResolver multipartResolver() {
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        return multipartResolver;
    }
}

The test should pass and give you output of

4 // from param
someValue // from json file
filename.txt // from first file
other-file-name.data // from second file

The thing to note is that you are sending the JSON just like any other multipart file, except with a different content type.

The method MockMvcRequestBuilders.fileUpload is deprecated use MockMvcRequestBuilders.multipart instead.

This is an example:

import static org.hamcrest.CoreMatchers.containsString;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.mock.web.MockMultipartFile;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.ResultActions;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.result.MockMvcResultHandlers;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.multipart.MultipartFile;


/**
 * Unit test New Controller.
 *
 */
@RunWith(SpringRunner.class)
@WebMvcTest(NewController.class)
public class NewControllerTest {

    private MockMvc mockMvc;

    @Autowired
    WebApplicationContext wContext;

    @MockBean
    private NewController newController;

    @Before
    public void setup() {
        this.mockMvc = MockMvcBuilders.webAppContextSetup(wContext)
                   .alwaysDo(MockMvcResultHandlers.print())
                   .build();
    }

   @Test
    public void test() throws Exception {
       // Mock Request
        MockMultipartFile jsonFile = new MockMultipartFile("test.json", "", "application/json", "{\"key1\": \"value1\"}".getBytes());

        // Mock Response
        NewControllerResponseDto response = new NewControllerDto();
        Mockito.when(newController.postV1(Mockito.any(Integer.class), Mockito.any(MultipartFile.class))).thenReturn(response);

        mockMvc.perform(MockMvcRequestBuilders.multipart("/fileUpload")
                .file("file", jsonFile.getBytes())
                .characterEncoding("UTF-8"))
        .andExpect(status().isOk());

    }

}

Have a look at this example taken from the spring MVC showcase, this is the link to the source code:

@RunWith(SpringJUnit4ClassRunner.class)
public class FileUploadControllerTests extends AbstractContextControllerTests {

    @Test
    public void readString() throws Exception {

        MockMultipartFile file = new MockMultipartFile("file", "orig", null, "bar".getBytes());

        webAppContextSetup(this.wac).build()
            .perform(fileUpload("/fileupload").file(file))
            .andExpect(model().attribute("message", "File 'orig' uploaded successfully"));
    }

}

Here's what worked for me, here I'm attaching a file to my EmailController under test. Also take a look at the postman screenshot on how I'm posting the data.

    @WebAppConfiguration
    @RunWith(SpringRunner.class)
    @SpringBootTest(
            classes = EmailControllerBootApplication.class
        )
    public class SendEmailTest {

        @Autowired
        private WebApplicationContext webApplicationContext;

        @Test
        public void testSend() throws Exception{
            String jsonStr = "{\"to\": [\"[email protected]\"],\"subject\": "
                    + "\"CDM - Spring Boot email service with attachment\","
                    + "\"body\": \"Email body will contain  test results, with screenshot\"}";

            Resource fileResource = new ClassPathResource(
                    "screen-shots/HomePage-attachment.png");

            assertNotNull(fileResource);

            MockMultipartFile firstFile = new MockMultipartFile( 
                       "attachments",fileResource.getFilename(),
                        MediaType.MULTIPART_FORM_DATA_VALUE,
                        fileResource.getInputStream());  
                        assertNotNull(firstFile);


            MockMvc mockMvc = MockMvcBuilders.
                  webAppContextSetup(webApplicationContext).build();

            mockMvc.perform(MockMvcRequestBuilders
                   .multipart("/api/v1/email/send")
                    .file(firstFile)
                    .param("data", jsonStr))
                    .andExpect(status().is(200));
            }
        }

If you are using Spring4/SpringBoot 1.x, then it's worth mentioning that you can add "text" (json) parts as well . This can be done via MockMvcRequestBuilders.fileUpload().file(MockMultipartFile file) (which is needed as method .multipart() is not available in this version):

@Test
public void test() throws Exception {

   mockMvc.perform( 
       MockMvcRequestBuilders.fileUpload("/files")
         // file-part
         .file(makeMultipartFile( "file-part" "some/path/to/file.bin", "application/octet-stream"))
        // text part
         .file(makeMultipartTextPart("json-part", "{ \"foo\" : \"bar\" }", "application/json"))
       .andExpect(status().isOk())));

   }

   private MockMultipartFile(String requestPartName, String filename, 
       String contentType, String pathOnClassPath) {

       return new MockMultipartFile(requestPartName, filename, 
          contentType, readResourceFile(pathOnClasspath);
   }

   // make text-part using MockMultipartFile
   private MockMultipartFile makeMultipartTextPart(String requestPartName, 
       String value, String contentType) throws Exception {

       return new MockMultipartFile(requestPartName, "", contentType,
               value.getBytes(Charset.forName("UTF-8")));   
   }


   private byte[] readResourceFile(String pathOnClassPath) throws Exception {
      return Files.readAllBytes(Paths.get(Thread.currentThread().getContextClassLoader()
         .getResource(pathOnClassPath).toUri()));
   }

}